As you get old and start dating older chics, the chances of them having a kid(s) get greater. Before I had a kid and dated a chic that had an infant, it was pure hell at first dealing with the kids father. He constantly knocked on her door. Waited outside to confront me when I left. His claim was always he wanted to know who was around his daughter, which to me was he wasn't over his ex. It was months before I even met his daughter....I'm come when she was asleep and leave before she woke. So it can be a pain in the ass. I have dated other chics with kids and it wasn't that bad.
One thing that causes the biggest issue is you can't just up and do shit. Spontaneous trips and stuff dont happen.