One of my friends is going out with a guy 25 years older than her.
It's not that unusual, it happens all over the world, all throughout human history, and even happens in different primate species (not a 40 year gap because lots of them don't even live that long but old males mating with females who have only just hit puberty is common, yet it's very rare for young males to mate with old females, except in species like the bonobo).
