what i think and the possibly-probably outcome of this is... at first, ml loved the mc (and he might be already obsessed with her at this time due to past encounters or love at first sight), but since the father wants to prove the og fiance's worth he made him and mc engaged, as explained. ml, furious and jealous, but also doesn't want the mc to know his true borderline obsessiveness went to become a priest. but for some reason (probably, almost killing the og fiance and is probably staying at the hospital), the ml was able to marry mc.
he's very secretive cause of his immoral way of being obsessive and he doesn't want the mc to hate him (probably, when she learn his intentions) or maybe he thought the mc still loves the og fiance, which he doesnt want her to know the truth.
that's why this story is kind of like she knows but doesn't truly know unless words comes out of him, and he just rather choose to stay silent.
is this gonna be crazy x crazy or victim x crazy. i dunno, i just thought this was the obvious, but i could also be wrong... maybe they'll add characters in the future...
this is so messy