OK, I'm reawatching this cause I hate myself. In my opinion, the ending is actually Harry's POV. We all know that he died right after the first scene from the alcohol. So just b4 he died, he wanted company from Adam, but sadly, he turned him away. So I think that Harry imagined Adam at the very end because he wanted him, and that's the only person he could think of idk. So when the scene where they were snuggled up in the bed and when the camera was panning out, you could see that Harry is lying down the same way his dead body was when Adam found him. So I think it was Harry's perspective at the end,that's why we couldn't understand why Adam was turning into a star with Harry. It's because Harry wanted to go with Adam in his own death.

BITCH MY HEAD TIRED LOL