Just friends advice ?

So there's this guy I've been friends with for three years and I've always kind of had feelings for him and he's expressed physical interest in me in the past but I know he doesn't romantically like me. As of late I have practically fell for him and I can't get him out of my mind. He knows how I feel but just wants to be friends. And he's being super chill about it, like he's super respectful and isn't making anything awkward. It just sucks for me becasue just staying friends with him is starting to just hurt and make me sad and idk what to do :(