A dream like that can fuck you up.
Back in high school, I had a dream that was too real. I tend to have hyper vivid dreams to begin with, even now.
But this one? Fuck.
It was a love story. No specific person, it was an imaginary girl that my brain cooked up for the dream. We met, dated, fell in love. And it kept going. Getting married, having kids, and in such detail that it is still in my memory as strong as some things that happened for real.
She died in the dream and I woke up just sobbing uncontrollably. An entire fucking life crammed into a few hours of sleep, however long the rem cycle took.
It changed me. I like to think for the good, since it made me much more willing to work in a relationship, to put in the effort it takes to be a good partner (well, my definition of such any way, might not be the same standards that others have, I dunno).
It also made me willing to end a relationship that isn't working instead of clinging to the idea of being with someone. Not that I never had trouble letting go, but on average, when it became obvious that it wasn't going to work, I could step away and not carry any animosity or regret. I think it's a big part of the reason I can be friends with most of my exes.