In reality, divorces happen, spouses/partners die, partners can be abusive to their partner or child etc, and if you love someone and love that child and are willing to help parent that child, there is no harm in it. Being a stepfather alone is not a cause to think someone is a cuck.
But, if you are a woman who sleeps around, you have to be realistic about the possibility of pregnancy. You have access to birth control and condoms. And even if those fail, abortion is an option (albeit there are access difficulties in some states and provinces, but most de facto bans of abortion fail on appeal). Sleep around all you like, you have ways to prevent pregnancy and in the event you do get pregnant, you do not have to carry to term. That being said, should you choose to carry to term, your choice has consequences and you have to take more responsibility than you would. You have to figure out how to provide for this child, and accept the fact that yes, you will not be a first choice for most men, including most men that would be your first choice, so you may have to lower your standards. If this is too much for you to handle, if you'd rather not worry about child support/putting education career on hold/being less able to find a partner to your liking, then you had your chance to choose birth control; you had your chance to have an abortion.
Pro-choice means pro-responsibility, as there is no choice, no freedom without responsibility.