No one is saying that Delta should require two passengers on the same PNR to sit next to each other, but if they choose to do so, then let at least one person sit in the row behind them that is now empty because 2B moved to 1B to be with the spouse.

And in another scenario that I have frustratingly experienced twice now, if a couple are 1 and 2 on the upgrade list, and there is only 1 seat left in the reduced inventory available secondary to the 50% rule, and consequently only one on the upgrade list can clear because of the 50% F rule, override the rule, clear #2 in addition to #1 , with the provision that #2 sit next to #1 . That does not impact anyone else in that cabin in any meaningful way but sure rewards diamonds traveling together.