Women expect to be rewarded for loyalty, but we're often not. Studies have shown that men move jobs far more than women and it doesn't negatively impact them; in fact, they usually move for a better package. Women think that if they stick around, good things will happen when in fact, there's no evidence for that.

Additionally, we assume that other women won't be as unreasonable as men when it comes to family responsibilities and there's no evidence for that either. (There's just not a lot of data because not as many women bosses.)

If you ask for what you want and don't get it, please also ask your boss why the younger woman is being given what she wanted when she doesn't have your proven track record as a worker. It's not reasonable to deny a reasonable request without an explanation.