I don’t really have an example right now that’s directly comparable, so don’t take this the wrong way and suggest that I’m comparing lying about birth control to pregnancy resulting from rape, but… Consider a rape victim who goes through with the pregnancy and has the kid. Maybe they recognize that the child is part of them and they really love them…but the child is also part of someone who did a terrible thing and/or might be an overall terrible person.
Obviously a father loves his child, no matter what, but forcing a man into becoming a father without warning or consent is a terrible thing to do, for both the father and the child. The father is now left with option 1 of being a part of the child’s life and hiding his resentment toward the mother from his daughter, option 2 of being honest with his daughter about her mother’s sleazy actions, or option 3 of choosing the path that he actually wants for himself while fulfilling his legal obligation to support the child. This woman robbed him of the choice to live the life he wanted to live. It’s just like the sleazy men who rob women of their fertile years by pretending they want to become a father with them, all the while planning to dump her for another woman when she isn’t so young and attractive anymore.