I'm reading the newest in the Monk series. A woman was killed who was having a 15 year affair with someone. Here's a conversation between the SIL of the BS and Monk.
Dinah (the BS) is a beautiful woman, but demanding in...in her requirements." She said the word delicately, implying a deeper, more personal meaning. "She left him no room to fail. Perhaps he wished for someone who could be a friend, simply to listen to him, and hshare his interests without the incessant need."
And then Monk's thoughts.
"An ordinary, pleasant-faced prostitute, just as lonely, just as familiar with the taste of failure, would seem like a godsend. It would at last be someone to laugh and cry with, for once without judgement, without expecation of anything except fair payment.
Would Dinah have even begn to understand that? Probably not.....sometimes it was the ease of no expectations, of allowing a person to fail and still loving them the same way....
That to me sounds like the author "understand" cheating in a way that most of us BSes don't!