
Heiner has a very big inferiority complex towards Annette. He always thought and still thinks that he's so inferior that no one can possibly love him, because even he doesn't love himself.
That's why when Annette told him she loved him he did not believe her and wanted to hate her but he couldn't and he's confused, he doesn't even understand his own feelings. He forced himself to hate her and blamed her for things she didn't even know about because if he were to admit his love for her he would feel guilty towards his younger self and all the people who died because of her father.
As a result, he thought that the only solution that would satisfy his conflicting feelings is to keep her by his side, but for that he needed to break her so bad that she wouldn't have the energy or strength to leave him.
He didn't know anything about the real Annette, that's why he didn't think she would dare to unalive herself. What a toxic idiot

Hopefully you can read it soon! You don't have to forgive him. He's in limerence, he was so obsessed with her that he has this ideal expectations of her when she turned out to be someone she's not, suddenly it feels like glood gates open, everything shattered, its like the only thing keeping from snapping. Then he puts this show on himself like he's trying to be the ideal version of her and himself, not knowing he should be himself. Ended up disappointed

I feel uncomfortable seeing her sleep with that dress and him being on the bed with his shoes

Right! Usually those dresses are worn with a corset, how can she breath I understand that when he comes to her room out of the blue during the day she can't change her clothes just for a nap, but at night?? Why ?
I wonder if the illustrator didn't think of that or was simply too lazy to make her change clothes
Does anyone know if there's a novel of this?
Hopefully you get the answer to this, let me know when you do please (=・ω・=)