Long term relationship& dreams

I got married at 18, he was 19. It's so weird because yes I'm very happy with him but lately thoughts of people in my past have come up. Which in this situation is from high school (since I got married right out of it). & I haven't seen this person in years & when we were "talking" we were never anything more than that. It's odd because ill randomly have dreams of this person and in my dreams this person will be telling me they want a life together and in my dream I'm happy with that. I know fully well that in real life this person has a family of their own as I do ( we now have a daughter). But in my dream a it's so weird, like I'm so curious and I so want this person and when I wake up it leaves me like, what the heck ? Anyone experience something like this ?