First off, I'd never say never. My wife and I began our relationship convinced that neither of us wanted kids. She was the first person that I had any sort of relationship with that shared my wish to not have kids. As time went by, however, we both gradually came around to the idea. We were together for nearly 13 years and married for 9 before we had our first daughter. We now have two girls aged 2.5 years and 3 months. I'm well into my 40's, though my wife is almost 7 years younger than me. I feel like waiting until later to have the kids was definitely the right move for us. I can't imagine having kids when I was younger. I was too focused on other stuff, although now I can't imagine not having my girls in my life.
Before meeting my wife, I had several relationships, long and short term, but inevitably one thing or another ended them. Usually, it was some combination of my atheism, my politics or not wanting kids. The no kids thing seemed to feature more prominently than the others in every break up. My advice on that front is that if you're serious about not wanting kids of your own (at least for now), don't get involved with a woman that does because it will inevitably become an issue. For me, the only time that it wasn't was when I was involved with a woman that had a 4 year old and didn't want any more kids. I was pretty crazy about her at the time, so I was willing to try to work around the kid issue. She had full custody, so it still seemed very much like I had a kid to worry about all the time in that we couldn't just up and go do whatever we wanted whenever we wanted. That didn't last long.
