Friends all said I would regret it. 5 months later...?

I was with my previous girlfriend for 3 years. We were happy, that wasn't the issue. The issue, in the end, was that we had different ideas, goals, values, morals and things of that nature. We got along pretty well, we had fun, but I decided that in the long run it would be a mistake to marry her. Perhaps because of how many times my father has divorced. Anyways, I broke up with her. Yes, her feelings were hurt for a bit. No, we aren't in contact anymore. The thing is, my friends, my family, even a few people that barely new me, said I would regret it. To this day I don't regret what I did. I miss her from time to time, sorry for wasting her time, but no regret about breaking up with her. I had, in my mind, a good reason. I guess what I'm asking is, when looking at the future to make the decision to/not to marry a woman, is it common to regret breaking up with someone? What did I overlook? I honestly have no idea why my friends say I would regret breaking up with her.