Boyfriend engaged in an act of procreation, albeit novel, the effect of which was merely delayed. She exercised her option to continue the pregnancy. He can’t make her NOT exercise the option any more than he could compel her to have an abortion.
Unless he had a contract in advance relieving him of financial responsibility, he is going to be a daddy with all of the obligations that entails. Even if he did have such a contract, I don’t think a judge would uphold it because there will be a child now who is biologically his and who will need support.
Caveat emptor.
Yep, once your sperm is out there and touches an egg and it happened with your permission... game, set, match.