Thinking about how unhealthy/abusive/broken relationships are a core part of Deltarune's story.
Kris and the Soul, two beings who shouldn't be together but are forced to be by people more powerful than them, Kris hates the Soul and its control over their body, they beat it, they throw it in cage so hard it leaves a bloodstain on the carpet, they're disgusted by anything that reminds them of it, but at the same time they don't want to and/or can't just let it go or destroy it because they need it, the Soul was denied it's own body and has arguably even less agency than Kris, it can't speak or move without them and so can't even ask anyone for help or explain itself and if you want to go further, copes with the abuse Kris subjects them to and their helplessness to stop it by taking it out on Noelle in the Weird Route, the relationship between Kris and the Soul is toxic for both parties involved, mostly because both refuse to/are unable to communicate clearly beyond subjecting each other to petty jabs and violence
Toriel and Asgore who went through a very ugly breakup and are coping with in in different awful ways, Asgore being neck-deep in denial and love-bombing Toriel while telling himself if he can just get it right, if he can just make her remember how she felt about him, then everything will be going back to normal, Toriel going full scorched earth, trying to avoid confrontation and when it happens anyway trying to get out of it as soon as possible, starting a relationship with a guy that's been in town for like two days, getting sloshed at her house and not even realizing that she's neglecting her kid who's obviously going through something
Carol Holiday and everyone in her life, Noelle is terrified of her and her omnipresent control over everything in the town, she's grooming Kris into doing something they don't want to do, holding a promise over their head to keep them in line, Rudolph says he loves her but doesn't want to leave her alone with their now only daughter, because Carol can not and should not be trusted around children and he knows that
And even on the smaller scale, Lancer and his physically and emotionally abusive dad that has him desperately try and search for any sort of father figure that will actually care for him like a father should, Rouxls trying to force a relationship in every chapter and failing because he only ever considers his own feelings and not his chosen partner's/partners', Ralsei's extremely messed up view of his and Darkners' in general relationship with Lightners, just obedient toys who should go along with everything a Lightner says because after all that's what they were made for and they're not really people anyway, Spamton and Tenna, Jevil and Seam, Spade King and Queen...
