When I was around 21 I slept with a guy who was 25.I really dont regret it either, it was the best sex I've ever had in my life.It was a ONS, my first and last one.
Currently bf is 8 years older than me. Though when we started dating he'd already had his birthday and I hadn't had mine so he was 30 and I was 21:-D. His previous girlfriend was only about 9 months older than me too. Always wind him up he needs to keep up with younger women
Ironically....I'm the mature one:-D
I was 20, he was 48 pushing 49. No strings.
As long as both people aren't attached and it's consensual sex then I don't really see a problem.