Yes. This does seem to be the case that where there is a largish age gap between the couple, it only works when it's him that's older. I think this is because biologically women are geared to maturity and effectiveness in their male partner, a form of protectiveness; men are geared to weaker and more vulnerable, bringing out their protectiveness.
Sorry, this isn't PC, it is anathema to feminists, but I'm afraid biology will always play the biggest part, not fashion or political emphases. Women can put up with an older man far more than men can stop themselves wanting someone younger.