Life offers choices, true. I can opt for chocolate or vanilla ice cream; I can live in New York or Los Angeles. Such choices often result in unexpected consequences like food poisoning, getting mugged in Central Park, or car-jacked in Hollywood. I did not CHOOSE to be poisoned, mugged, or car-jacked simply because I chose to eat ice cream or live in one of those cities.
Somehow, under your logic, a man has no obligations and responsibilities until the child is actually born. Then suddenly he is fully obligated simply because he had sex with a woman, even if he used contraceptives which clearly indicated he had NO intention of having a child. Even if he was no longer involved with the woman and thus unaware, suddenly she can present him with a child and demand he take full responsibility.
When you've talked about the "law requires" you are making a fallacious appeal to the consequence, because LAW can be changed. When you state "there is a child' you are making an appeal to emotion; ignoring many instances where children are raised and fully supported by a single parent alone. When you state he must accept responsibility simply by having sex, you are merely affirming the consequent; i.e. If he has sex he might have a baby, he has sex; therefore he agrees to having a baby.
All fallacies and none address the issue.