Spoiler!
ML was also in love with him in the first timeline. But his family was awful, so he was using the girl (with her consent) as a fake girlfriend to trick his family into believing she was his weakness.
He never loved her, always loved MC. When MC die, he spend years getting revenge for him. He was begging MC not to die during the dying scene, but MC did not realize before he was too wounded to hear and see correctly. I was not able to access the last chapter, but in the one before, they found something about time travel, so... Oh, also, MC kinda transmit his feeling when he guide espers and when the ML takes his hand, he instinctively guide him, so ML could feel all of MC last thoughts, but MC was deaf because of the explosion and had no clues about ML real reaction.
Just thought I would drop this
(Disclaimer, the explanation isn't mine. I just copy pasted it here)
