I think in most situations when they man is older it is received better by society because 1) guys mature later than girls, so it could put them at more of an equal playing field maturity-wise and 2) in heterosexual relationships men are viewed as the “strong” and “supportive” ones, whereas women are the weaker ones who need supporting. So, if the man is older he is perceived as wiser, more financially stable, which fits right into the societal stereotype and makes sense to people. A younger man and older women doesn’t as much, and therefore confuses people. But hey, fuck societal standards