you know when someone chases you and you ignore/reject them and suddenly when they turn away from you you realize you were liking the affection & attention they gave you so now you want them back and you use whatever excuse like "i see u as worthy of my time and effort now" just to convince them to go back to you??? yeah that's called being possessive & narcissistic... that's what he is. he couldnt stand the idea of someone who was filling up his ego no longer caring for him even more so now that a lot of people are appreciating her
--sorry for the long reply
Spoilers:
Not sure but from the raws he has some weird obsession with her. He seems to hate her and want her around him so he can feel better about himself because they used to both be chubby and supported each other happily until he started to lose weight and became cocky and a dick. She was still a little chubby and seemed to deem her as less than her. Also the watch hes so focused on remaining clean was gifted to him by her (MC). So... yes and no... i think
I'm still confused as to why the ex is so obsessed with her. Like he dumped her right?