Your bf is gay. It is possible that he's bi and unaware he has a crush on a younger man, but it happens. I've seen lots of "straight" guys get crushes on men they admire.
Your bf admires this guy, and you've already seen that his admiration for this younger man is more than his whatever-it-is for you.
Bail. Even if you don't believe that he's got homosexual tendencies, he's already shown you your "place" in the heirarchy of his life. You are second fiddle. Either bail or accept that you always will be.
Or in the immortal words "Honey, he's just not that into you."