Being equal in modern society means having the ability to choose one's own destiny without society placing unfair expectations on them. It's possible that there is a genetic component to temperament, but one of the things that modern research has shown us is that variation within groups (even sexes) is enormous. To simply say that 'women are usually happier at home taking care of the kids' reduces what we actually know down to a level where it's borderline incorrect. It also reinforces historical gender roles that limit people's choices.
I think the mistake you (and many many others) are making is in trying to link decisions like this to sex at all. (I'm not talking about research here. I think research is valuable. I'm talking about how we interpret things in every day life) Why not just say that's how you two worked it out without referring to sex? I think that once you've linked those decisions to sex in your head, you're more likely to view other people's decisions through the same lens, and once enough of us do that, we end up restricting people's options, even unintentionally.
We're all individuals, whether we're male or female, black or white, gay or straight. Sometimes many members of a group have a similar trait, but that doesn't mean all (or even a majority) of the people in the group are the same. It's an easy way to categorize in our head, but every time we think that a group acts in one way, we're treating people as a category and not an individual.
Why can't we just take everybody as they are, and not try to explain their decisions as 'that's because they are a [group]'?