I've been all over the place looking for this manga, and i would appreciate it if you helped me. I don't remember much but I remember that the plot was this man who was being possessed by the ghost boyfriend of the guy he loved (im not sure if he loved him at first or not). I know its not much to go on but i do have this website (because im new here and don't know how to work this thing)
https://40.media.tumblr.com/tumblr_m5iro03dhQ1r4zb2yo2_1280.jpg

Thank you so much for your help!

Based on that image I'm pretty sure you're looking for Ikemen-kun to Saenai-kun, but the person who possessed the MC was the other guy's deceased girlfriend, not boyfriend.

Thank you so much for your help! and I realize that now thanks my memory of it isnt so good.

Yeah, it's easy to get muddled up about that kind of detail. Anyway, it's a nice enough story, if a bit underdeveloped. Glad I could help!