Peter likes getting divorced. Not even because it makes him feel more lonely, more importantly, it means he can bring it up in conversations and make the other person very uncomfortable.
Mikaele: Hey, Peter, long time no see, how are you?
Peter: Oh, I’ve just gotten divorced!
Mikaele: Uhh… Sorry to hear that?
Whenever it starts to feel like it’s been way too long since the divorce to keep bringing it up he goes to propose to Elias again. (When he’s very lucky Elias will say no and he can start talking about his failed proposal.)