Anybody else have a hard time committing to one girl?

I'm 29 and by this age your family starts asking you "When you gonna get married?" "When you gonna find that special someone". I've had one girl I really loved when I was 24-25, but I couldn't commit so we had an open relationship. That ended badly, to say the least. Then for years I tried to get her back, I did, and I thought I was ready to commit but I wasn't. So now she hates me for good. I've met a few other girls I really liked but I also couldn't commit. One of my biggest fears is turning 40 and having a mid-life crisis because I didn't adventure enough when I was younger. Plus I haven't even figured out a career path yet.

At this age I'm really starting to understand woman better, and it took so much work to get to this point that I feel like if I were to commit it would be too soon. I feel like I don't have many years left to "play the field" but at the same time I wouldn't mind a relationship with a cool girl.

What are my fellow miscers thoughts on this topic?