Well it's hard to tell from the details you've left out, but it sounds like your way of expressing your affection is to tease him, and he has trouble recognizing that. It really doesn't matter WHY you love him, but it does matter that you find a way to express your affection so that he can "hear" it. Do you actually say "I love you?" -- as simple as it sounds, that might be a good place to start. One thing that might be a factor is that it's sometimes hard for anyone to express those kinds of feelings: when you tell another person something like that, you're sort of "laying your heart open" ... vulnerable. That can be quite uncomfortable, because you're not protecting yourself from the other person's behavior -- they might be cold, or indifferent, or even cruel in response, then how would you feel? But that "open heart" is the key to everything in relationships -- if you can't tolerate that discomfort, you really can't have a romance. So rather than tell you exactly what you should say, I would advise you to look at your own mind and heart: do you "hold back"? Are you protecting yourself from being hurt? Are you a "smart alec" because it's less dangerous than being in love? You're the only one who can answer those questions. But that's what he's listening for: he wants to hear your heart open up in a way that lets him in.

just tell him you didnt only fall in love with , you fell in love with things that he does, his goals for his life and above all him as a great person. You love him because he makes you happy and he makes feel beautiful inside.