I don't think the ML is in love with her so I don't his behavior is weird or progressing too fast. I would say he's mostly in lust with her and as a bonus finds her presence comforting. Probably because he's been alone most of the time. Also it's kinda weird that just because he showed her a lil kindness that she's willing to bump uglies though. Desperation maybe? Yeah that's my 2 cents.
I think it's more of a survival thing. He's the only nice person she's met in the world, but he's weak to her appearance. So she has to seduce him in order to survive, since he can kill the zombie things
I don't think the ML is in love with her so I don't his behavior is weird or progressing too fast. I would say he's mostly in lust with her and as a bonus finds her presence comforting. Probably because he's been alone most of the time. Also it's kinda weird that just because he showed her a lil kindness that she's willing to bump uglies though. Desperation maybe? Yeah that's my 2 cents.