Now that the ex is back in the picture, you and your girlfriend (GF) should sit down and discuss what your role will be in your stepdaughter's (SD's) life. You should discuss ground rules for SD (i.e. treat you with basic respect by obeying you, saying "hi" and "bye" to you when you come and go from your home, that she needs to make eye contact with you and have a polite expression on her face when you talk to her and she talks to you, bedtime, consequences for breaking rules, etc.). She should treat you with the same respect she shows her preschool teacher/daycare provider. You should let your GF take the lead on disciplining, but definitely iron out rules for SD and consequences for breaking them behind closed doors, without SD present. Encourage her in getting to know her dad. When you do something nice for SD your GF needs to make sure she (SD) says a polite "thank you" and GF should thank you too.

This article might help you:

http://www.associatedcontent.com/article/19343/a_guide_to_getting_along_...

I disagree with #3 because I think all stepparents at some point have to discipline the kids, even if it's only when their spouse isn't around. Teachers, coaches and babysitters have to discipline the kids they're watching, and they aren't related to the kids by blood (in most cases) so stepparents should be allowed to have some discipline role, no matter how big or small (and provided the discipline is reasonable). For now though, I suggest (based on my experience with my SDs) letting your GF take the lead on discipline and you be backup and only discipline if she's out of earshot or not present to do so, and in the meantime, try to establish a relationship with SD that is workable for both of you.

it feels like a slap in the face after all you have done and tried to bond with this child it is tough.The same thing happened to my ss and i we got along great and i really felt like there was a bond their and than his mother reared her ugly head and he dropped me like no tomorrow.It is hurtful but a bio parent will always come first before a stepparent no matter if its good for them or not you basically have no say in the matter.If i were you continue on with what you are doing with her she will eventually come around and know that you have been there for her.

Do you spend any quality one and one time doing fun things with her? She's only 4, she's going to go through phases. I'm having a similar issue with my husband and son (his Stepson), but its caused more by how my DH was interacting with my son. Things have turned around the last few days since I spoke with him and he is making an effort to spend quality time with my son, one on one and has changed how he handles him. I'm not sure if you're saying her coldness is a result of her father coming back into her life or as a result of you asking her not to think of you as one. Either way, you need to try to reconnect, and for kids that age the way to do it is spending quality time playing with her, doing what she wants to do and making her feel loved.

"Nobody will ever win the battle of the sexes. There's too much fraternizing with the enemy"

I wrote this a long time ago and I hope this helps with your problem. It may not reflect your exact situation but you'll get the idea:

The situation with my step-kids finally got to the point where I decided that my efforts to raise them was futile.

First I told my wife in private what I was going to do and why.

Then I stopped investing myself, time and money in their upbringing. I realized that by conscious choice I could cease being responsible for them or their actions. Neither would I take credit for how they turned out, good or bad. I simply stopped interfering in their lives. This is not to say if they would start a fire on the living room floor I would not intervene. But if they did not do the laundry as scheduled I ignored it. Nor did I do any of their chores. If the trash overflowed in the kitchen - well tough. Mom dealt with it when she got home.

You will be absolutely amazed at the look on a kids face when s/he realizes you don't care enough to even tell their bio-parent they did something wrong. And you'll be amazed at their future behavoir and attitude towards you.

I stayed friendly enough and taught one how to drive when she was old enough. But they could no longer blame me for the consequences of misbehaving just because I saw the misbehavoir. I never told. If they were caught in a infraction it was not my fault. They began to realize that they were responsible for their actions because of what they did not because I caught them.

I would talk to my wife in private if I had issues, but once she made the decision I backed her up 100%.

Once the kids realized I was no longer the ogre they thought I was their attitude changed. I was not their friend, but neither was I the enemy. They came to realize that I had not done those things to irritate them. They in fact missed the things that they had come to depend on me doing. Permission to go to the mall when their Mom was not home? "Sorry, can't do that".

Their mother slowly came to realize that I wasn't overreacting to their actions. In fact I wasn't reacting at all. She came to understand that she would have to control the situation and she did.

With that things got much easier around the house.

Billions of kids grew up in the world without help from me and turned out just fine.
*********************

There's an exception to everything I say.

That age is not known to be calm time. Believe me her behavior will improve as she enters into ages 6,7 and 8 when they are most pleasant ( little helpers).
I'd hang in there, not like she is 18 and has a fully formed personality or anything. You have an opportunity to build a strong realtionship with this small child due to her age.
The personality of a 4 year old isn't even formed yet !!!!

My ss is 7 and he acts as though I'm non existent, only when he wants something. I have tried to disengage , only to be hurt more. His bio dad keeps telling him things like I'm not a real dad and he shouldn't love me . Horrible things, how do I know this? because it slips out when my ss talks at night to my his mom. Its insane, if we have him for more than a couple days he loves me and hangs all over me, but as soon as he comes back from his dads, he treats me as if I'm invisible! And now that Im working nights its worse. My wife tries to encourage him to engage with me and he only does if she is there just to please her, he is always hanging on her with a real insecurity. Ive tried everything and Im at my end, it hurts so bad. I have been married for 2 years and with my wife and my ss since he was 2 and his dad just keeps filling his head up.