Barely legal implies they were recently illegal. Nearly illegal implies that they will soon be illegal. I don't know the max age for concent, but being with someone that far outside my age doesn't really interest me.
Edit: thought about this more.....
It's illegal to fuck a corpse.... the people on the right are almost dead.
I definitely don't want to fuck someone to death.
In Dutch it's pretty much the same, but with a bike instead of a horse. "Op een oude fiets moet je het leren." And is also used in that same way figuratively.
I feel like consent from someone suffering dementia would have the same problem as consent from someone who is completely shit-faced drunk, making it not really consent.
I remember reading a while ago about a case where basically that exact thing happened. A guy got prosecuted for relations with his wife of a long time because even though they had been together for a ton of years, she had dementia and therefore couldn't consent. I'm not sure how it played out, but chargers were filed at minimum.