My daughter said to me when I met my husband, mother what will happen when he turns 40. I told her if I can have 10 happy years that is ok, nowadays a lot of marriages don't even last that long.
At that time, guys I am now talking 30 years ago, someone had written a book about older women and younger men and she wrote she was happy with this arrangement, 10 years happiness was fine with her. I know not an average thought but look around you how many people are happy for at least 10 years.
My European mother never saw a problem, she knew other people, especially in Europe, that it was no big deal and they ended up having a long happy marriage.
Of course in the US this always has been a big deal except for older men and young women. Thank you Demi Moore to show us another side.