Low Sex Drive

Hi... I've been dating my boyfriend for 1 years and 7 months. At first we had sex all the time. Every time we would see each other a minimum of 1 time we'd have sex. Over summer break I lived at his house and we slowed down a lot to maybe 2-3 times a week. After returning back to school I no longer see him often, only on the weekends. He is very horny when I see him and wants to have sex right away me on the other hand I could go without. I am still very much in love with him but I just can't seem to ever be really horny. Any suggestions on how to help?? We've tried pretty much everything (sexually).