i have a crush on one of my boy mates what sould i do

i'd keep this great guy as your friend. guys come and go but friendships can last forever!

I think 당신 should ask him out for sure

This is why it's important!
사랑 또는 Friendship??
if 당신 choose 사랑 your 심장 will be enjoyable 'cause 당신 got the guy 당신 want, but we never know how long we could keep together
but if 당신 choose friendship, that guy will never go anywhere from 당신 no matter what because friendship never dies 또는 ends

so it's your decision! but to know he loves 당신 더 많이 than a friend, 당신 could see his reaction 또는 ask some 사랑 related 질문 :)

Why don't 당신 tell him how 당신 feel about him. Tell him your feelings and be respectful and gentle with him.