I've looked at this question rather seriously. I'm not exactly clear what femininity is but I do know two other answers to this question.

Nora Vincent wrote the Self Made Man - her experiences as a man for one year. What she said was that she couldn't believe the constant competition and challenges. In terms of biology, I call that just the mindless evolutionary drive for dominance. In those terms what a woman is for a man is a safe harbor. When home, there aren't the constant challenges of the day. This might be a heads up that even if a woman has a job where she must be aggressive, she probably shouldn't take it home.

Now in my terms, it's a bit different. I work on long term human survival so I have to study some odd stuff. In ways this is sociobiology. In other ways, it's practical morality. Both are slippery. It seems counter-intuitive but what a man wants most is to be loved... even perhaps more than to have someone to love. It's conceptually difficult but makes sense in terms of biology. A man will do anything for love. They say "give a woman a house and she will make a home", well give a man some love and he will build that house. Heck, he'll build that house just hoping it will lead to love.

In the larger scope, I see two instinctive behavioral potentials in humans. They are easy to see in yourself, other individuals, and pretty much any group. They are (1) the commonest, red of tooth and claw competition commonest to nature and (2) the cooperative abilities humans developed after leaving the trees, which required the large brain that evolved then. Humans only have a future as more than animals if we use the cooperative instincts. We have strategies from philosophies and religions to go along with the instincts. Most modern moral systems are built on the cooperative strategies... though actions may revert. We have all we need but we need to know it is a choice between the two. Women can dictate that choice more than men. For love, a man will choose that. Without love, a man tends to war. Ladies... peace is better for you and your children, and you get to choose the future. Give men love and they will create a civilization where humanity can thrive.

More of this nonsense in "Genetics For A New Human Ecology" and at zagwap.