^ I know that the issue is fertility. While impotency may not cause infertility…it can make the conceiving a child more challenging (although now there are various options and treatments). The point here is that if you’re aware that you have a problem (WHATEVER it may be)…that will directly affect your spouse…you have an obligation to inform him/her.
Don’t remember the details, but it’s possible that perhaps the guy was previously married…perhaps that marriage failed…and things became known. Perhaps he confided in a member of the family. Somehow, it came out.
And there are situations where one finds out about something…indirectly…through another or several other parties.