I feel that I should have experimented a bit more in my youth.
I married my first long term boyfriend.
I find myself daydreaming about situations that happened when I was at Uni or similar, when I could (should!) have slept with someone else but didn't and feeling a sense of missed opportunity. I guess it's curiosity to some extent. At the time I had the idea that not having slept with multiple people was desirable? Not sure why now.
So not really an AIBU, I guess I'm just interested to know if other people sometimes feel this way?