Gilglim suggested the following:
Mrs. X is a good wife. She sees the PBS documentary in passing and later that same week, she comes home from work late to find her husband in a jealous rage. She calms him down and explains why she had to work late and he is able to verify her alibi. As a part of 'making-up' they have sex and she swallows and finds that it is delicious. She quickly determines that Mr. X's jealous/killer sperm is what she really wants. So she starts off being more flirtatious with other men... and this does the trick for a while, but she finds that it starts taking more and more just to get him jealous.
By the end of the story she's pulling trains and acting as a fuck-doll for the local high school football team... all of this right under her husbands nose. ANYTHING to make him jealous so she can get some more of that killer sperm. :-)
Anyone care to write it? I'd love to read it.