I think it depends on the individuals, and love doesn't consider such things. MrsW is one year older than me..........
I know a couple with a 14 year gap. He is now 63 - looks older, and with three kids under 10. She is much younger looking than her 49 years and he is usually taken as the grandfather - this happens all the time when they are out together.
But then again, wealthy old blokes can pull women much younger than themselves. A bloke at work has just pulled this off and he's not even wealthy. He is late fifties, she is mid twenties.
