Why can't I get rid of feelings for my ex?

I keep getting recuring feelings for my ex even after they go away like we were inseparable we were basically identical in every way almost never fought or anything then out of nowhere she changed and started fighting with me and broke up with me we were still friends for a short time after but we recently stopped talking I wouldnt nessacarly say I’m still in love with her like I was but I do miss her alot and if. I had the chance I would definitely give a redo on our relationship to make a long story short