Dreaming of my ex!?!

Hey guys so I really need some advice. So I’m in a relationship, we’ve been dating for over a year and it’s serious. So lately for the passed week or so, I’ve been dreaming about my ex. I have had non stop dreams about him and I’m just wondering why. He was my first love, kiss, everything. We dated for 3 years on and off. I haven’t spoken to him in about 1 year and 1/2. I obviously had to stop talking to him because I got into a relationship. But I don’t know why I keep having dreams about him! I don’t miss him nor want him back in my life but what do I do to make it stop!!! I feel so guilty dreaming of my ex and waking up to my boyfriend. The dreams aren’t ever anything sexual but I wanna make it stop:( no negative comments please, it’s not like I choose what to dream.