What do I do about this guy?

So theres this guy im really good friends with and were in different schools..... prom is in like 6 weeks and apparently hes going to ask me... I know that i'm most likely gonna ask him but I just want us to go as friends... but i know people are gonna expect us to get together or whatever and apparently he likes me but i really don't like him in this way....... He is the loveliest guy I know but im just not attracted to him. What do I do? Please help me! If i reject him it could ruin our friendship!