There are so many memories now that feel like dreams. It's difficult to say which was real, and which was imagined. Or even if the memory is real, which parts happened exactly as I remember it?
There's this article I read before that stated that since our memories are just reenactments of what actually happened, each time we remember something, it's like playing a VHS tape again and again. Each time, the tape gets a little more worn out. So ironically, the more we remember something, the less accurate that memory becomes.
Eventually, the memory gets spotty. Holes get filled in with imagination. And we begin to hallucinate a better or worse thing than what actually happened.