Student Exchange Programs

ok as you might know from my other questions i have been going out with my bf for about ten months. i love him (in teenage terms). i know he cares about me a lot to, and i would never want to hurt him. but lately i have been feeling attracted to another guy. i thought this was harmless enough (or at least that was what i was being told), but it just keeps getting worse. it doesn’t seem to be a minor flirtation, i am really falling for him. i don’t know what to do. i don’t think i could break up with my bf he means so much to me, and he is one of my best friends. i am 15 though, and i want to try new things. oh and the guy i like is an exchange student, so he leaves in about five months. please please please help? i know this is stupid, but for me it seems important to be nice.
also the exchange student might like me. we were talking for a while today at a swim meet, and afterwards he texted me, and was really nice. thanks again.