Christmas is primarily for children, although even couples without kids are still expected to do a lot of "festivity" related stuff that falls primarily to women. And, most men are more than happy to eat a big holiday meal (typically made and cleaned up) by women. That's because "home keeping" has traditionally been seen as "women's work" - and most guys are used to leaning into that. I'm sure there are some men who don't care anything about holiday festivities but also that the vast majority of them are fine with letting their mom or some other woman they know carry the weight of creating that, even if they are single.