At what ages does a 10 year age difference between a male and female become acceptable romantically?

My girlfriend is 42 and I am 52. We first met many years ago the summer I was 35 and she was 24. I don’t think the age difference mattered even then, but she seemed very young to me. She had no idea how old I was but assumed I was only about 4–5 years older than her as most of our mutual friends were that.

But it occurred to me recently that when I was a young semi-“professional” summer camp counselor at age 21–22, my girlfriend would have been one of the children (10 or 11) !!! Egad!!!

Even ages 19 and 29/30 doesn’t sound very “kosher” but I assume it could work. But to me, the 24 and 34/35 age difference seems like it was indeed about the first time it might’ve worked.

So, in your view, at what ages would a t0-year age difference been a non-issue? .