I don't mean to be the "your information is wrong" guy but it's not necessarily true. Generally you'll have 3-5 dreams a night, and you can remember at the least bits from all of them. Rarely will you ever remember the entirety off a dream, especially because dreams are very hazy in their own. Your memory sees them as useless filler so it deletes them within 15 minutes of you waking up, usually, unless they happen to have some vivid emotional connection.
On the note of me, I don't remember much of my dreams. About a month ago, I had a dream where I had six with a friend I'm not even attracted to. Today I took a nap, though, and I dreamt that my previous ex (the only one I'd really gotten any distance with, and now have negative feeling towards) started showing up in places I visited often with his new boyfriend. It was somewhat distressing in the dream, because I felt harassed, really, so I guess you could call it a nightmare. Real nightmares, though, I had one about a month after me and him broke up, and it was obviously about me and him, I felt bad for cutting myself off from him. before that it'd probably been four to five years since I had what could be described as a nightmare.

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