Dreaming of Ex

I keep dreaming about my ex 😕 as much as I’m trying to get over him. We stopped talking for almost a year now but been having small little convos from then and now (we spoke a few months ago the last time). I keep dreaming about him 😭 like constantly (every other night) why am I dreaming about him ??? He’s in a whole different relationship and every time I see him in my dream I get closer to missing him.