I have an inkling that it's a misunderstanding. If he is obsessive enough to follow her to the real world then he can't have killed her.
He is the ‘if i cant have you, no one else can!!’ Kind of guy
I up @nelcys theory I've seen tropes like this, and judging from how much ml loves mc and is protective of her (I mean her flashbacks only shows she was confined but never abuse or r*ped which shows how he aint tht kind of trash) it's impossible to go 360 just coz she attempted to escape. Prolly som sort of dark magic or impersonation happening here
Yeah but just think, guys with that kind of mindset would confine their interest, chain them to a room and not let anyone see them. The yandere type. What good would killing them do? They're just letting their target escape through death. So yeah, i have a very strong feeling she died by someone else's scheme and right before her death she was lied to that it was ml who wanted this to happen. Since her opinion of ml is probably rock bottom, she believed it without doubt.
The truly obsessively in love kind would never let their lover die, and would follow them to hell if they had to but would never let them go.
Ohhhhh tbh this could be the twist
Oh he’s sweet but a psycho , a lil’ bit psycho
his poison but tasty~
Now I wonder why the ML killed MC in the isekai timeline??