Agree with blueskies... a lot of the problems, imho, in step or "blended" families is responsibility is given, but not authority. 

Given her kids annoy the crapout of you, I asume you will want to correct behavior. Will she agree the behavior is annoying? Will she get upset whn you correct them?

What involvement does the deceased father's family have with the kids? If they are involved, have you met them? What do they think of you? For that matter, what does her family think of you and the potential to have authority (not just responsibility) over her two kids?

Save your money and retire early. Wait a couple of more years and find a woman with no children. It’s not worth the headache.

i don’t mean to sound pessimistic but your GFs kids are still so young which means you have YEARS of having them around yet. I met DH’s kids at 10 and 11 which was bad enough.... they are now 16 and 17. The only reason I am still here is because I can see the end in sight and at 18 we won’t be housing them or financing them. I wouldn’t even consider adopting them even if you do marry your GF. You never know what will happen down the track and adopting them means you are on the hook financially if you and GF/Wife split. It is too big an undertaking and I would strongly advise against it. Think also about the impact on your child. 

I knew my husband for 10 years before we married. I can't believe how quickly some people marry, especially when there are kids involved. If you don't mind a long courtship, you can play it by ear. I know you said the kids are becoming attached, so I understand it might be hard to leave after 5 years or so. But when there are so many people's lives involved, I don't know how someone can't take it really, really slow. And I sure wouldn't move in together if you aren't willing to marry -- it seems to me getting out of that would be just as hard as divorcing when there are so many kids involved.

But it sounds as if she's willing to let you parent, and that's a good sign. But give it a good long time to simmer!

Life is risk. It sounds to me as if you are a sensitive and caring man who is looking at all the aspects in a sensible and reasonable way.

All kids misbehave at some point- it is only adults who 'grade' that misbehaviour according (mostly) on how it impacts on them. Hence, you didn't like the way they were at the beach because you witnessed it and it made you uncomfortable. That discomfort, that doubt, that need to seek the opinions of others- that is not going to go away. It will be a feature of your life always. Even if you adopt these boys, you will never be their father. Just let that sink in. 

No one knows how this is going to work out- but the pressure seems to be there from the get go. Don't let that pressure exert too great a force on your life. You did not cause the death of her spouse (at least I hope not!) so the damage that has been done (and losing a parent that young is hard) cannot, and I repeat, cannot be undone by you. In stepworld all that will happen is that you will get all the consequences of that damage, but none of the means to put it right. You will always be a bystander.

I think you need to take this very slowly indeed. Plan to marry in ten, fifteen years time- then work towards having a relationship with your SO that is exclusive of your joint families. Have fun, support each other, but allow time to be separate from those kids on both sides. Just date.

Make these plans open and clear- revise them when things go good or get difficult. Keep your finances separate. Work towards common goals but have your own standards.

Then when the time has gone by,  and you can deal with the way she manages her own children, only then do you think of marrying. I suggest holding fire on the adoption thing until they develop a relationship with you that tells them they woud like to be adopted. It does hppen- but I think they should be of an age where they can be more fully involved in that decision.

This is my advice- you probably won't be prepared to wait. But you should take all that emergency equipment with you, because it is very steep and rocky in stepworld, and only a few get to the summit.

Stepdads generally have it much easier than stepmoms...which is mostly what you'll find here. Plus, this is a venting site...so you're seeing the worst of the worst from people (mostly women) who are at the end of their rope. Might be good to hear perspective from guys who are happy as stepdads to balance things out. 

I agree with you not wanting to string a widow with 2 half-orphaned boys along. That would be rather cruel. 

You mention that your GF has no problem with you disciplining the kids.  My question is, does SHE effectively discipline them?  If she doesn't, then you are in for a very rocky road.

First, I think you are smart for thinking of these things now. Many of us thought situations would improve organically, and found they stay exactly the same. I do have a few thoughts on it, though.

1) A big lesson I have learned is to acknowledge that I am biased when it comes to the kids in my home. We must understand before anything else that our own kids will always seem better than all other kids just because we got to raise them the way we wanted to. No kid is perfect, but we parents influence our own kids to be the type of imperfect we can live with. Many of us do not get that luxury with stepkids. In your case, maybe this will be different eventually since there is no father to influence them, but in many cases, they go back to a parent who does things very different to us, and also, our spouse was once married to that person, so they are at least a bit ok with that way of things because they used to live that way, too, so we end up with really annoying stepkids and a spouse saying, "I see no problem. I think this is cute." Again, maybe you will have a bit more influence in that way than most of us. Only time will tell, but right now, you are feeling the effects of the fact that they were raised to be a brand of imperfect you did not choose for your own children. In your case, maybe the things you want to change are things their father loved. Maybe it will be more difficult for you. We cannot know this yet.

Does it mean automatically that the kids are bad, or have some psychological problem? No. They could, but it could also be that they were raised in a way that you think nobody should ever be raised. This is something I struggle with when it comes to my stepson. In your case, if it is upbringing, you will see these problems reduce as you have more influence. Be mindful of your bias as you form opinions, and make observations. Maintain some detachment when you do this, as if you are a scientist and they are your research subjects. I do not mean act standoffish, but in your mind, maintain enough detachment at least for a while, to honestly evaluate what is happening, taking your bias into account. I know this is hard, but try to do it. It helped me understand my own situation better.

2) Acknowledge biology. It is our instinct to provide for our own kids, even if it is at great cost to us. You would give your own child the last bite of food you had to eat, the last money in your pocket, the only shade on a hot day, even if you wanted these things yourself. Every parent would do this for our child, and most of the time, we think it is like nothing. I realized how different this is with stepchildren when my husband gave his son a bite off a plate of food he and I were sharing. I was immediately livid! How dare he give him that chip?! It was our chip! I was not even hungry, but I was still mad that he let his son have food from our plate. That was the moment I asked myself, how often did I hand my own half eaten plate to my always hungry son without thinking about it? More than one time each week, I think. How many times do I give my daughter a sip of my drink because she thinks it looks good? I cannot even count this. Yet, my stepson is handed one chip I do not even want, and it is as if he took all the money from my pocket. This is not rational. No, it is not, but it is biological.

The point is, everything we do for a stepchild is more expensive to us than anything we do for our own child. I try to tell my husband this when he talks about how ungrateful my kids are even though his kid is the snottiest brat I ever met (he really is unpleasant. Nobody likes him. It is not me only.) Young children are always ungrateful to some extent. They all expect to be cared for. This is biology, too. When they are older, they give back more, but when they are young, they take. We think nothing of this for our own kids, even as we try to teach them manners and good habits, the fact that we get comparatively little back from them to what we give is not in our minds much. With a stepchild, we are overriding our instincts every time we do something for them, and we expect something back, and they will not give it to us because they are children. If their parent does not step in with that acknowledgment, we can become quite bitter at the whole thing. (I know this happened to me.)

The reason it is important to keep this in our minds is because then we can ask ourselves, is their parent acknowledging us? Do they understand what they are asking us to do? If they do not, can we help them to understand this? Maybe this can be a conversation we should have before marrying or living together. I wish I had done this instead of making these observations when I was already there.

3) Do you honestly know what your SO expects of you and of this arrangement? What is your goal for it? Do these have a lot in common? Are both of you genuinely willing to do what it takes to make this work?

OK, what I mean is, she probably wants you to take a parental role for her kids since their father died. You seem to know that. Does she understand what that means, mostly that it does not mean you will simply help her maintain what she and their father decided for them? Does she understand that if you are in a parental role, you will have just as much say in their upbringing as she does? That means that if you think the misbehaving kid actually needs a psychologist, and she just thinks his behaviour is quirky and fun, your opinion is as important as hers and the right thing is to go to a psychologist and rule out problems. It means that some of the ways she raised them are going to have to change to accommodate you, and that she must understand your parenting style and your needs are valid as much as hers are. Do you think she agrees with all this? Can you have this conversation with her?

Make sure you have finances figured out. I know you'll be completely dedicated to the boys, but she may want things for them you don't. You want raising expectations, where finances are going? You paying for her kids to go to college? First car? Etc.

DH and I had a lot of this figured out, but we still have awful moments where things will flare up. I completely love my skids, but sometimes the headache drives me insane. I don't think kids should have TVs in their rooms, he does, they had them first, so I lose that one, but their lack of sleep directly affects their moods and behaviors. Just things like that.

Make sure all parenting expecations are talked through, manners, employment, not housing them without working past 18, whatever it is YOU need, don't just assume that she'll go with it when you get there, make sure you've already discussed it and have a solid plan in place for when that happens.

Financially you need to know where she sees the money going. Is she responsible with money? I thought DH was too, but he likes buying the girls stuff, it's caused some distress as I am SUPER frugal and don't see the need to buy lots of extras. Whereas he does, he also thinks we should buy them their first cars. I laughed, then we compromised at getting ONE FAMILY car that they may utilitze until they can afford their own. 

Just make sure you've talked through things like that. I get along famously for the girls (life would actually be good if it wasn't for the psychotic BM causing issues, drama, throwing the skids into emotional distress, and now court due to BM and GBM caused drama). Love the girls, the lifestyle is still rough, and there are still days where I want a break from the girls when DH doesn't. Not due to lack of love, but because suddenly having the two kids can get exhausting and make you miss how much more freedom you had before.