How do I [M23] cope with the end of a relationship with someone [F22] that was unhealthy/unsustainable long term, but I was objectively happier when I was with them?
Long story short, I dated this girl for several months and it was a really great experience until the very end. We were excited to be with each other, went on all sorts of fun dates, and every aspect of our relationship felt great.
Then she broke up with me out of nowhere. Just 24 hours earlier she was telling me how happy she was with me, etc etc, and then blindsided me citing all of these mental health issues and childhood trauma that made her feel like she couldn't be loved. Whether or not this is true or was just an excuse doesn't matter, the point is that the relationship was ultimately doomed and wouldn't be healthy for either of us to continue.
My issue is that, looking back several months after the breakup, I was objectively happier when she was in my life. I'm pretty content with my life as is, but I really can't deny that my life was better with her in it. Even though I acknowledge fully that it would have been unhealthy to continue, I still can't cope with the fact that I miss her and was happier when I was with her.
How do I cope with this and move on?