I like my a relative of my BFF

Okay so my BFF has an uncle who is 17 (I’m 16) and he transferred to our school. He hung out with us since he didn’t know anybody and we got really close. Currently, he has a GF but I like him a lot and idk what to do. He’s leaving for college at the end of the year and I probably won’t see him much after that but I don’t want to tell him anything since he has a gf and since we are good friends.