Why do I find myself not masturbating when I become emotionally attached to someone?

I'm a very young guy and I've been infatuating with this girl over the past 3 weeks, but it hasn't been since the last week where we've really gotten closer. Anyway, I haven't masturbated in at least 5 days, and I always do it daily. In fact, I don't feel as horny as I used to. Even if I see extremely hot girls around college I don't get an . Why is it that I don't find myself as horny as I used to be before I started liking my potential girlfriend?