Prepare to rage hard.

Quoted from a feminist blog:

"I went on a sex strike for five years after our kid was born, as a way to maintain my autonomy and agency once I realised the kid thing really did economically trap me into my (reasonably happy) marriage with a (reasonably egalitarian, yet clueless) guy. I just couldn’t give up that last thing of myself – if I had, then he would have owned all of me, not just my free childkeeping and house labour.

(And I didn’t miss it. Caring for kid, going to school, making art took up all of my energy.)

When I did want to have sex again, I made the political decision to engage with men outside of the marriage, as well as the husband. If I was going to engage in (the oppressive act of) sex, then I would have it how I wanted it and with whomever I wanted it with, so as to expand the boundaries inherent in the system of non-consent."

source: http://blog.iblamethepatriarchy.com/2011/07/18/a-bit-of-lighthearted-fun/#comment-180274

tl;dr: feminist stops having sex after giving birth, later decides it's ok to cheat outside of the marriage.