Because I'm looking for someone to settle down with, while a girl who wants to have fun and feel excitement would probably find him to be boring. Look for girls who are wanting to settle down more.
Also, some of it probably has to do with your age. You're 19. Most girls your age are just looking for flings and are therefore going for the exciting type of guy. You notice how she used the words: "marry when you're OLDER." When they're ready to settle down, you're the type of guy girls would go for, which is something they do when they're "older."
Don't take it badly though . . . . unless you want flings yourself and aren't interested in anything serious, you're the type of person who will be able to establish long term relationships, while the guys who are getting all those girls now will probably never have a healthy relationship in their life.
I'm the female equivalent of you. Men don't date me who want to have fun. Men who want long term relationships are usually the ones who find me interesting. (Or at least the ones who think they do.) But since that's what I want as well, I don't really consider it a bad thing.
And oh, by the way, I didn't have my first kiss until I was 20, so don't feel bad that you haven't kissed anyone yet. Maybe it comes with being people like us.