[The Owl]

OP, it's not them, it's you. The attraction to the "new" girl has everything to do with how you're feeling, nothing to do with the girl herself.

You might be right that letting your girlfriend go is a mistake, she also might not be the girl for you, or you might not be emotionally ready to make that kind of commitment. Get your own [censored] dealt with and the rest will fall into line.