does he like me? what do i do in that case?

so the boy i'm talking about is a very good friend of mine. but during the last few months it felt like there was more to it. he acted very happy while i was around, he came almost every recess to my desk just to have a chat, he stood up for me, he gave me flowers and always hugged me goodbye. i didn't even realize he might like me, but everyone told me 'omg can't you see he's so into u!' and shit.. yah. and lately he's been keeping a distance, we talk less, our conversations are different, he doesn't hug me that often, he just waves to me in school to show me he knows i exist. and he talks to me about other girls. he might have liked me before (cause he has other close female friends he treats very good,too) but now i have no idea what's going on in his head.i thought about asking him if he likes me, but then i lost courage. i could ruin our friendship. what do you think ?

Sounds like he liked you (no doubt about it, from the way he treated you), and moved on. If you like him back, reciprocate. Initiate hugs yourself, smile at him and try to make time to be around him.
If not, don't think much about it and move on. Your friendship will not be ruined.