Why do I miss her? 27M

I broke up with a girl I dated for 4-5 months. It was 8 weeks ago and I still regret it…why? We didn’t even have sex. I met her at a bar, she wasn’t initially my type but I grew to like her a lot. And as we got more serious I was still confused on whether I liked her enough to continue dating her, so I ended it out of nowhere. But I think about her everyday and I dream about her occasionally. Idk what to do.