Idk anymore

Ik he’s loosing feelings. I’m doing everything I can and he’s admitted that me loving on him is “too much”. I have every reason to leave but no part of me can let go and I’ve completely lost myself because of him. He’s like an addiction I can’t live without but he’s not giving me the love anymore. Yet I can’t let go because I don’t want someone else to have him. How can someone be so heartless to the ONE person that loves them despite their every flaw and love them in every way possible? To have to force my love for him inside just so it doesn’t go unappreciated or me getting in trouble for it is mentally draining.