Dreaming about an ex can mean all sort of things.
It might be you have unresolved feelings toward your ex.Maybe you’re unsettled with the way things ended between the two of you,hence according to Dreamstop, it might represent the fact that you need to make peace with your ex.
Sometimes It’s not about your ex, it’s about you.It also means that you’re neglecting yourself in some way or there is something in your life that's making you unhappy.You’re afraid someone else will hurt you again.
there’s something in your old life with that person that you miss — and you want it back or you just miss the parts of your life with them,those things you did,those time you've spent together.It also indicate and made you realize that the current relationship you have right now will go down to the same path and you need to change your relationship course.