> woman live in a society where men perpetually behave like we know what's best for them.

Everyone lives in a society where everyone else behaves like they know what's best for them. Men currently happen to have more power to enact their plans, but it's about power, not about gender, and all people who seek power think that they know best.

> a perfectly plausible alternative interpretation, which is that he knows what's best for his girlfriends better than they do for themselves.

We are literally commenting on the article confirming using hormonal contraceptives increases the risk of cancer. So if your partner is using these you basically have two options: 1) ignore the issue and maybe not even mention it to her as this could be misinterpreted as influencing her decision, 2) address it out of pure concern for her future, even years ahead when you're no longer together.

3) bring it up to make sure she is aware of this possibly new information, and assume she will use it to inform her decision making? What do you think I meant by providing input to her decision? What on earth made you pull out the straw man that you can’t even influence them?