Why can't we just smile and wish the gentlemen well when they say they're going to go do something they like this afternoon? This is so obvious. Because we never get to go do something we like.
Men can leave. The perpetually parturitional can't. They are always pregnant, and thus bringing a baby and the associated discomforts and restrictions along, or (more often) nursing, and thus unable to be absent for more than a few hours, and totally unable to be absent without thinking they shouldn't be.
I've been pregnant, nursing, or both since March 2002, which means I'm barely out of my rookie years on a CSPP scale. This is why I have something like absolutely no sympathy for the "I just need some down time" argument. Believe me, I need some down time. But there is no way for me to get it. So it turns out I don't need down time. And you're going to have a really hard time convincing me that anyone else does.
I get it that life isn't fair, so all this isn't to say that a certain man in my life doesn't get his afternoons, days, and weekends away. I try not to resent it, but that really hasn't started working out for me yet. So I try for the next noblest thing, which is not to ruin it for him by crying, screaming, throwing things with the conscious intention of breaking them, and shrieking about how sick I am of all this and how totally unfair it is that he gets to not only occupy himself with employment of his choosing, engage his mind in exercises both practical and academic, socialize with colleagues, and participate in adult life (including interaction with women who would not debase themselves by living as I do), but also casually announce that he'll be gone at these times for this number of days to do things that he enjoys doing. Right now I'm generously ruining it for him only with dark moods and snippy reminders of my endless sacrifices whenever I see opportunity to slot one into a conversation.
I'm sorry to say that I weigh each paternal absence with miserly precision in units of self-determined necessity and reciprocity, and the children suffer under the foul moods that result when the number I come up with is low.