I imagine the statement

Single women have longer, happier lives than women with husbands and children, while it's the opposite for males

is support for this conclusion:

Older women tend to be more single though as they realize after time that being single makes them happier.

I've heard this stat before, but, just to push back a bit more, I have to wonder if the conclusion follows from the evidence presented.

Men have higher crime rates and are exposed to more violence. I imagine more violent men are single. Hence, the happiness of the single men demographic might be weighted down by this subgroup.

I suppose there is a way to test this hypothesis. We would need to see the standard deviation of the happiness of single men. Maybe there is a subsection of MGTOW men who are single by choice who are as happy as single women.