I call the “1/2 your age + 7” rule the “socially correct rule”, or something like that. Meaning that it’s the youngest a MAN can go without people wondering about him (I know there are lots of exceptions!!)
it isn’t applicable at the extremes of age (like your 80-year old example) but seems to fit pretty well from 20-50 or so. Examples: If a guy is 30, he could date a 22-year-old without too many odd looks. But an 18-or 19-year od would probably get him some looks. If he’s 40, then the “minimum” age would be 27 before people starting thinking things of him.
But of course it breaks down, like any approximation. So a 10-year old man can only date women 12 or older? Yeah, it gets silly. A 80-year old man and a 47 -year old woman would definitely raise some questions too.
I say it only applies to men because it is generally more socially common for men to date somewhat younger women (as in the above examples) but not the other way around. Heck, I’m dating a girl 9 weeks older than me and a friend of mine said that would bother him! 9 weeks!! Give me a break.
Though there are all kinds of exceptions and contrary examples, I know I know. Hey, I didn’t make up this “rule”!!