Grown men- what age do guys stop wanting girls only for sex at?

My father has told me that all teenage guys (or at least, 99% of them) just go out with girls for sex Honestly, is this true, or is he just saying this to prevent me from getting knocked up, an STD, or heartbroken? Also, are there some exceptions in which teenage boys/young men want girls for anything other than sex, and truly do love them? I want the truth, it's okay. Is this all really true? I love my boyfriend and if he just wants me for sex, then maybe I'm pitiful, but I really don't care as long as I get to be with him. Is he just very crafty at seeming as though he has feelings for me? The fact that him and I think similarly would help a great deal, after all... Please help me. =) I would like to see a variety of answers. I will pick the one I find the most helpful.