This reminds me of a true story involving my goodself.
Four years ago I was moving down to Florida from Boston and there was a woman at work and on my last few days at work started telling me about her wanting another baby aged 42 but her then boyfriend had had a vasectomy. He said (according to her) that she could have artificial insemination from a donor and he would bring the child up as his own with her - she had tried twice but it had failed both times. She kept talking about this, adding she was thinking of just meeting someone for a one off to see what happens....if she gets pregnant she would tell the boyfriend that the AI treatment worked. I plucked up enough courage via a text 2 days before leaving for Florida (I had left work now) saying i would be willing to help her out and have nothing to do with the baby if successful. She replied positively and on my final day in Boston met up and I (ahem) became a sperm donor....
I texted her 4 and 6 weeks after and she replied that noting had happened.....
I wasnt surprised at the negative result given that I had a vasectomy myself in 1995......