Why did I become this way?

I used to be mad clingy, needy, impatient, not really trusting and not understanding with guys. Now I like a guy who is in the National Guard, he works part time and we talk a lot. I'm not attached to him the way I was with other guys, I understand that he's partially enlisted and anything could happen, I'm not nearly as clingy and I don't get upset if he doesn't text back right away etc. etc..