people will get mad even about relationships that don't have significant age gaps and don't risk defective children. iirc i think second cousins are fine in that respect yet the outrage remains. i think this is just one of those norms that once was practically reasonable and now has solidified into being totally unquestionable. there is also some kind of social trend that seeks to problematize men being in all kinds of different relationships, which has probably made things worse and more controversial these last ~35 years