(you are both guys) he is your best friend, you have no secrets from each other. But he hides from you that he is gay and has been in love with you for a long time, he is terribly jealous when he sees how you communicate with other guys or girls, but never say anything about it because you are just friends. he is jealous of any gender because he does not know whether you are gay or not

now he is watching from the side as you are talking to some girl and he is terribly jealous