I don't know if I am losing feelings

I have been with my partner for nearly a year now. I have always been extremely interested in them throughout our relationship but struggle with what I think is relationship OCD so I sometimes obsessively wondered if I still loved them. A couple days ago I suffered from what I think is a mental breakdown? I've never had something like it before but I just kept crying and crying for no reason. After this situation, I felt completely numb towards my partner. i started avoiding them for a little bit and would get snappy at them. I don't know what is wrong and how my viewpoint changed so quickly because if I think of leaving them, I instantly begin crying again and I don't know what to do. Am I facing the side effects of a breakdown/burnout or have I lost feelings quickly?