@marjan, I'm so sorry about your situation...
I have read almost every comment in this thread and I really thank you all for all the kind words and wisdom you have shared. I am in the same situation, too. I am with a man who has two girls, one 7 and one 10, from his previous marriage. The girls have always been nice to me, the younger one still tries to compete with me for their dads attention, but the older one understands better. We have been together for almost a year and a half, and we have been living together for half a year so far. Things are not looking pretty since we started living together though. He always thinks I see him all the time so I feel like he's taking me for granted. He started wanting to see his kids more and more and I only asked him to arrange it in advance and let me know. We had a massive fight in early December and I started staying at my parents every now and then to get away from him and his kids (whenever I don't feel like seeing them). I have no issue with him wanting to see his kids, but I have an issue with him not sticking to the plans. I am not sure why, but I am the kind of person who likes routine and stability and I'd like to know what is going on ahead of time. His ex-wife has also played a big part in our falling apart, she uses the kids as a weapon, like, if you don't do as I say, you won't get to see the kids. She doesn't like me being there and she changes the plans a few times and messed everything up, which greatly upset me.

As of a few days ago, we are now taking a break and I have moved most of my stuff out of his house. He said that he still loves me, we both cried. But he said that he doesn't want to always fight with me about the kids. He always accused me that I am not happy when he sees his kids, but I am only unhappy when he changes our plans without discussing it with me first! I want to be the first one to know everything, and first one he tells everything to.

We are now having some time off to reassess the whole relationship. I hate that love is sometimes just not enough. And that there are so many other factors that play parts in our relationships. Besides the kids issues, we get along so very well and we both love each other very deeply. I am utterly torn between wanting to stay and walking away.