When we meet my wife's lover he was a newly divorced man with no kids due to low sperm count. My wife was 38 back then and still capable to have kids and I must say it was somewhat strangely arousing to watch him slashing his huge load of thick and stick cum deep inside my unprotected wife knowing that maybe the doctors was wrong and he actually was breeding my wife... The doctors was right, nothing happened....
We talked about it back then and both my wife and I wanted to wait for the decision for what we did IF she got pregnant. My wife had her first kid with one man, her second with another man and the two youngest with me, so getting a fifth kid with her lover was something we actually talked about doing. And something I was prepared to do. But it never happened.