I had a very lucky escape from a relationship, because I didn't really grasp initially how the kids would be part of the deal. When I was about 35 I started seeing someone I'd known when I was much younger after meeting up accidentally in London -- he was living in California, and was separated from his wife. I think the children were about 8 and 6. We had a long distance relationship for about a year, during which time we started to talk about me moving to California, and I started researching job opportunities, etc. Obviously, I assumed that his wife would have custody when they divorced, and he'd see them every other weekend or whatever divorced fathes do. I also assumed that she would get the house and vast majority of their assets and a huge chunk of child support, so we would basically have to be living mainly on my assets and my income. But then I discovered that his assumptions of how we would be living were a little different from mine. I don't like like children, never wanted children, and had absolutely no intention of taking on any kind of step-parent role at all. He imagined I would be involved when he had his visits with the kids, whereas I reckoned he would take them to the zoo or the beach or whatever, and I would have my alone time then...Then he started to talk about how much a house would cost with a bedroom for each kid...What?!? He was expecting to have joint custody and they would be living with us some of the time! There was absolutely no way that was going to happen.
The funny thing was, he also couldn't understand that I not only didn't like kids, but I also was never, not ever, going to have his baby either.