I don't know If getting back together does really happen, but something interesting happened to me: I've met for a dinner with my ex girlfriend(she was my girlfriend for 2 years). I remember I was really destroyed by this break-up(it was back in 2015, you can probably still see posts here of me moaning, crying, etc). I had held anger and pity in my heart associated with this break-up for a long time, but one day I just texted her with birthday wishes, I was really kind and polite, and we decided to meet It was a really pleasant meeting. We went to a Vietnamese place, talked, laughed..And I don't really hold any pity in my heart anymore. I'm happy for her, I like her. However, we don't maintain contact as we used to do few years ago, but we're certainly "cool" with each other and we've left everything that was bad behind us.
Of course, we're not getting back together or anything but what I want to say is..That one day you actually realize that you can forgive and I mean it like..forgive for real and even be able to meet this person, talk, laugh. It was a great experience for me.