I think he is obsessed with her purity and thats why in the first timeline after marrying her he basically threw her away cause she wasnt pure anymore and now he is so obsessed with her cause he was already planning on having her for himself but she decided to go with another man especially one he doesn't respect so he totally had a meltdown
I also think he sees her as an object and just became angry and obsessed at having what’s he thinks belongs to him stolen away. It’s all about control and manipulation, once he loses the control he has over her he starts to go crazy.
I don't get why this guy is acting so obsessed with her when, in her past life, he was just using her and abandoned her quickly after the wedding. Can't he use the other princess to get ahead in the same way as he did with the MC in her past life?