Reality decides for them. Kids need food, clothes, health care, shelter. If the woman cannot provide for her kids then you will FORCE men to provide for her choice.
If you have a solution that does not FORCE men to provide for women's choices present it.
And you would force your own judgment upon them, removing the possibility of them making a choice you might even agree with. Obviously, in your world, freedom is for men, not for women, and men should bear no responsibility for their own progeny. Men will decide for them- whether or not they can afford a child, whether or not they should have an abortion, whether or not the father should support their own children, whether or not contraceptive coverage is a required part of health care plans. Men will decide!
And you're still talking out of both sides of your mouth when you propose we should stigmatize childbirth out of wedlock, bring back shotgun weddings, do away with no fault divorce. If that's not forcing men to take joint responsibility for joint actions, then what is?
You seem to think that men don't recognize the possibilities & responsibilities when they have sex with women, that they're somehow victims in all this. Hardly. The roles & responsibilities haven't changed much since ancient times, other than women escaping from being owned. The truth is that the liberation of women has actually reduced male responsibilities. Not so long ago men were held more strongly accountable for their action in this realm than they are today. Failure to "do the right thing" could have severe consequences, up to and including premature demise.
You also fail to recognize that welfare isn't forever, that it's usually a bridge, a temporary situation that the vast majority of recipients seek to escape, to move on, to get jobs & the better life that traditionally comes from it.