This, sadly, seems to be what Elly lives for. If there is one thing Elly does seem to actually enjoy in this life, it is the care and maintenance of grudges. The same woman who all but salivates at the prospect of her brother having a miserable life as a means of getting her own back for his having it mildly easier than she did seems to love it when John makes a complete bonehead of himself. That way, she can act all wounded, never actually tell the benighted idiot what he's supposed to have done and torment the dimwitted slob for days on end out of sheer malice. This means that the perfect marriage that Deanna idolizes and Liz wants to have is that of a loutish, immature emotional abuser who married so he could have a new mommy and a vindictive, manipulative paranoiac with a martyrdom complex who needs to feel upset to feel alive.
The reason that this is thought of as being a wonderful thing is explained in the "Please Love Anthony" letter when Lynn tells us that we wouldn't want to see Anthony and Liz actually behave as if they could stand each others' company. Simply put, Lynn does not understand or like romantic love and thus substitutes something she's familiar with: jerks feasting on each other like rats in a cage.