Yall why do i keep dreaming about this one guy🤦🏻‍♀️

I have a boyfriend and all we been together for like 3 years (were always on and off)but i keep dreaming about his old friend. Their not friends anymore or whatever. Back then he would cheat or just do stuff behind my back and that friend would tell him to not do me like that that im better then the girls hes cheating on with me this and that and one time we ran into each other at school and we were just talking laughing but ever since then we stopped talking but when this whole coronavirus started he started texting me telling me that i deserve better that im beautiful but then i stopped texting him for a while because i was just confused and didn’t want to be with him. But now my boyfriend doesnt cheat hes a good guy he focuses on work he sees me and all that yea we both had mistakes but its different now and were 16 but why do i keep dreaming about that guy 💆🏻‍♀️ and it’s constantly