Some guy who gives research results as an answer has had no experience himself and has not had any close friends with experience either. Throw the stats out, I have met women who have married younger men and have had natural, normal marriages. Don't care about what others think, and don't pay attention to statistics,that is the advice I would give.
Had I wanted to marry my younger boyfriend (a few years ago), I would have regardless of his age. We had other differences that had nothing to do with our ages so we went our separate ways.
Research shows that 34% of of all women over 40 are dating somebody younger than themselves. The operative word is "dating." Research also shows a very, very small amount will marry a man younger than herself. Give that some thought and it might give you insight into your question.