Husband and wife’s children finally grown, starting their own families, etc. Out of the house at long last.
Life is all good.
Husband returns to his home improvement projects, etc., wife returns to her writing, etc.
Finally socializing again, etc.
Life is pretty good.
Life becoming less good.
Life worsening with each passing week. Husband and wife grow bored.
With each other? With monogamy? Maybe.
Go see a marriage counselor, like they did way back when. Same counselor, now older, wiser, or, at least, more confident.
Marriage counselor insists on vacuum created by kids’ absence, etc. Makes silly suggestions re how to fill vacuum. Gives them worksheets, etc.
Husband and wife diligently follow suggestions, complete worksheets. Obviously in love, or, at least, obviously committed to the idea of being in love, they try their best to make it work.
Go on vacation? A cruise? Yes.
Have a threeway? Maybe? No.
Still bored, etc.