It’s better not to rush this. It seems they had a conversation which resulted in BF changing his mind about moving in together. It’s probably better not to push it. Live your life and let SD see that you’re not itching to move in on her territory. In fact, hold out until she’s the one begging you to move In with her dad. She’s going to feel bad when she realizes she’s the cause of her dad’s singledom. Enjoy dating him And also living in your own place, your own space and peace. Don’t rush to live with SD. Trust me, it’s no Brady bunch like you’re imagining. You guys won’t be one little happy family under one roof. It’s going to be hard.

This is a great time to watch and see how they are together.  If he ends up being enmeshed with her, a Disney dad or any other dysfunctional relationship dynamic, you won't be there in the midddle of it.  It will be easier to end it all if you chose.  

Don't see this as a rejection of you,.  Its not so far as you explained.  Its a dad doing his parenting.  

I’d call it quits. He already chooses 15 year olds opinion over his own and yours. She already runs the household and tells him who is allowed to live there. And he is ok with it. It will only get worse 

May not have been the best timing to mention your excitment to the daugther/in the presense of the daughter however that aside, I agree with the other's that I would consider calling it quits, or certainly I would have a major change of attitude - in other words make sure to go out there and happily live my life, be far less available to your boyfriend after treating you that way! 

When DH (then my BF) and I moved in together, literally one week to the day BM decided to move DH's then 16 YO daughter in with us

No one discussed this with me - not that I would have raised any issues with it - just like you had not raised any issues with your sudden change in situation

But I do remember with hurt that DH had actually expected me to be negative about it, and acted defensive from the moment he told me what was happening, even though it was the first discussion we had ever had about it! 

But on another note, belive you aren't missing much!

My life living with DH and his daugther soon enough turned into a nightmare

Just like your SD, mine was 'polite and respectful' to start.But this gradually turned into attitude, sulkiness, rudeness, to abuse

And DH cowered to her behavior, all out of that guilty divorced Daddy syndrom and need to be like a friend (rather than parent) to his daughter

To this day there is damage not only to the relationship SD and I have, but with DH & I there are hurts that will never fully heal

So, at a minimum, try to find time to see friends and family without your DH

Give him LOTS of space to be with his daughter, don't be at his beck and call, let him actually miss you and maybe regret how he handled the situation with you (yes his daugther's needs come first but he did not have to do that at your expense)

See how he handles your new attitude, and what will happen

JMHO

While not discussing the change with the OP was wrong, his decision was not.

Parenst should think about how their choices will impact their children.   Then make decisions based on what they feel is in the children's best interest.

Sorry double post

Seriously though, going through what you read, here is what I see. Keeping in mind that I was in your place, in a way at one time, in a slightly different situation. Its been 4 years for me, however, but I dont know how long you two have been together.

Flag #1. "I haven't bonded with her yet but she's only been respectful and well mannered so I'm not worried about bickering or arguing with her." You havent lived with her and you cannot see the future. You should definitely worry about bickering with her and arguing. Shes a teenager, you are new to her life. Teenagers ALWAYS argue, with everyone. Because they know everything and everyone else knows nothing. Do you have children? I do not, but experienced firsthand teenager-dome, and have a pre-teen in my life. 

Flag #2. "My boyfriend gave me a glare and it was uncomfortable". Um, yeah. As others have noted and I will repeat, you are not a mind-reader, what the heck were you supposed to say/do? You had no idea that they had completely discussed your move in, and nixed it and decided all this without discussing it WITH you. You were completely blindsided, and then blamed for it. That is a very big RED FLAG that gives you an inkling of what you have to look forward to in your future. Like as in forever. Unless you grow a backbone and nip this quickly. This would signal you to BACK OFF, stay away for a bit, see what happens whiel she lives there. That alone should tell you to look for another relationship.

Flag #3. "pause the moving in together while his daughter gets comfortable without her mom". Translation: while you sit on the sidelines as his "mistress", his new mini-wife will move in and become Daddys #1. She will take over the household and demand his attention, because now she only has 1 parent paying attention to her. Without mom around its all daddy all the time. Ive seen this at my place, when I first came into the household. "who the heck are you to change things, move things, add things?" was the attitude I got. If you are moving into a household, and plan on making it yours after the fact, you will more than likely meet with resistance, ESPECIALLY if the former spouse resided there. Add to that the mini-wife will not like sharing. Hello, children are resilient, they will ADJUST. "Getting comfortable" doesnt say adjustment to me, it sais "stay away mistess".

Red Flag #4. "he told me that his daughter had told him it was stressful enough without her mom and she didn't want to feel like I was replacing her"  There will be no replacing Princess Daughter Snowflake mini-wife, because once she moves in full-time, and gets comfortable, she will oust you. You will be tormented for a little while and she will delight in this game of "who is this woman taking moms place?" You will get to hear all the stories of how awesome mom is, dont you remember when mom and you did this and that.

Sorry to rain on your parade, but there are so many indicators.

Best advice - back off, dont move in, wait and see what happens. Read this board, search the term mini-wife, mini-girlfriend. Even under the best of circumstances things can get weird, but I just had a visceral reaction to those two making this decision without you and then glaring at you in your excitement...and then all the rest.

Good luck, let us know how it goes!

On one it points to the fact sd15 already runs the household. And you would be replacing who? Her biomom? That is bs. Her mother already opted to move ACCROSS CONTINENTS with her SO. SD is already asking too much of her father on an emotional level and he is unrealistically giving it to her. That spells TROUBLE.

To give you perspective(tho my skids were much younger ) my DH and I moved in one weekend and we expected the kids to adjust to the new situation( they had already spent overnights and 3 days straight as a couple with us). We had no problems. Ss12 I think once whined that he wished his mom would still live with his dad. The answer: but then you wouldnt have your two brothers and SF and your sister with SF. He thought about it cried at the thought and let it go bc he'd rather havr all of us in his life than his parents be together.(a crappy choice but that will be the choice for the rest of his life)

If you really love this man(sounds like it!) Then wait and ovserve for a few months.  Maybe by the end of the waiting/ observation period YOU will be the one ready to leave. 

From your BF's point of view, he has a major life change happening. So does his daughter. I think it makes sense to wait to see how this goes. You might not want to be part of this once you see how the household develops. Or in a few months, maybe your plans will be back on course.

He should have talked alone with you before this came up the way it did. Maybe he didn't because he's distracted and really anxious about how this is going to go and it just slipped his mind. Maybe he assumed you'd know your plans would have to be put on hold. But maybe this is a sign of how he handles things and maybe it's good you found this out now rather than later.

Regardless, I think you may have dodged a bullet. The timing is unfortunate, but three sudden roommates sounds like disaster to me. Give them time to work this out.

If she's polite and things go well, then you'll all be on better footing if you move in.