Often a man is keen for his wife (or girlfriend) to have a child not so he can be a father - god no - but because he wants a reliable home base. He will see the children as his wife's hobby, and she will facilitate his life. He will go to work if he works) in a wife-ironed shirt, come home to a meal she shopped for and cooked, sleep in clean sheets she washed and dried and put on the bed, and he'll leave his clothes lying around on the floor so that she can pick them up, and skidmarks in the toilet so that she can clean them. When she finally has enough and divorces him she will find out that you never know who you're married to until you tell him you want a divorce.
Maybe he'll come round late at night drunk, ring the bell again and again - the children will be crying for you to let their daddy in - and he'll go away thinking Job Done! Fucked her up there. He'll maybe chuck his job, do courier work and sleep on friends' sofas so he can't be found by the CSA - why should he pay any money to that bitch?
He'll find another girlfriend (he'll choose one with a job and her own place to live) and he'll be just as sweet to her as he was to his wife, and it will work a treat. He'll move in and she will facilitate his life. She'll believe what he tells her about his wife, the psycho bitch who won't let him see his children. She will believe he loves her, because he says so, but she will discover, as his wife did, that what he loves is having a place to stay and a woman to look after him.
So the thing is, when women are young they often think the best of people. including men. And men will present themselves as lovely. A lovely man is more likely to be housed and facilitated than a git. And gits they are, but they are camouflaged, very well, as caring, responsible men.