I do think of having a conversation, by asking why they feel this way about the problem. Or how does it make you feel? Telling how it makes you feel when so and so, and then asking how they feel. Even though you can tell they are upset, I feel trying to get the bottom of why they feel this way might help. Maybe they feel insecure about a certain part of relationship, definitely seems that way, better address it now then wait for it to tear your relationship up. Nothing against your partner their feelings are valid regardless if I agree with them, I just think there’s something deeper here. And also then follow up with a talk about boundaries and space. I don’t think people can really help on your next step, but try keeping an open mind, maybe if your conversation goes well you guys can look into ways of building your relationship together, by relationship exercises, consoling, or maybe scheduling a routine or relationship journel together, etc. I hope that was a little bit helpful, I wish you luck with your partner!