This is why Vanitas used to refuse romantic relationships. It was a haste. Ever since he got into a relationship with you he was on edge. Not because of you, he was entirely doing it to himself with all his overthinking. Just recently the two of you got into a fight about you trying to convince him that he wasn’t having a healthy mindset, especially in your relationship with him. But due to your harsh presence, your concern came off as pretty hurtful, which is why Vanitas distanced himself from you for a few days.

You tried to talk to him again and explain yourself, that you didn’t mean it rudely. But he seemed convinced that you were only saying that to manipulate him so you could toy with him…

"God, I‘m done with relationships, and I‘m done with you!"

he exclaimed roughly and turned away from you, his arms crossed, protecting himself.