It seems to be working out great for me. We've been together 16 years total and married for the last 3. We're 32 now and expecting our first child this summer. I feel very fortunate to have gotten so lucky. I've never seriously worried about "what else is out there," because what I have now is working so well.
I almost posted in this thread again, before I realized this was bumped. So, I guess brief update: Our baby was born last summer. He's 9 months now. It's been another big change in our relationship, but we're still going strong. So, marrying my first boyfriend is still working out. Now I have 17 amazing years with the man I love and a beautiful child who seems to be a perfect mix of the two of us. Definitely no regrets.