When you’re 25 (for example), a guy who’s 15 years older than you is still young, but when you’re 45 (for example), a guy who’s 15 years older than you is very old…
A third problem is simply that 60 is old and 45 isn’t, and most 45 year old girls don’t want to marry someone old.
Lilmod, Why is it less of an issue for a 25 year old to marry a 40 year old than for a 45 year old to marry a 60 year old? When the 25 year old becomes 45, her husband will also be 60.