Abortion- but for men.

Since it is only an option during the ~3 months that abortion is available... What would happen if the girl just didn't tell the guy till past then?

Not a biology expert, but how well can you hide pregnancy for 3 months?

I'd say, if the guy wants to stay committed, go ahead. If he doesn't want to help raise a child that was kept from him for a quarter of a year, he should have the option to just leave. Issue would be low long he's allowed to do that.... You'd need a perfect balance of power between the man and the woman at this point to avoid abuses rising.
Too soon and women could use shock tactics. Too long and men could play dumb.