Best friend gave me a love letter and a ring (we r both dudes )

long story short I was the extrovert who adopted the introvert , ever since then we have been Best bros but
Since the last few days he has been giving me compliments ngl I thought he was joking . Yesterday he slides me a letter and says "open when u r home" then he ignored me the whole day.
And he's too serious of a person for it be a silly prank

Ps: I'm straight