The truth of the matter is that for the most part, women are fungible. Meaning one can be replaced with a different one and life can move on ahead much the same as it was. It's like, as you say, a restaurant where everything sucks, is easily replaceable with a restaurant that doesn't suck. What really makes one woman more special than another one is our feelings for her.One of the great lies of Western society is the "soulmate". It is especially ironic that so many men and women subscribe to the concept, given that many of them don't believe in the existence of the human soul. The greater success rate of arranged marriages puts the lie to the concept; the "love marriage" is actually a rather inefficient means of establishing lasting, loving marriages.
So if she's special only to you, but not really anyone else, then she's not really truly special. If you start thinking someone else is special, and your wife is no longer special, then she will very quickly become uncomfortable about what is happening.
The one angle where they aren't 100% fungible is that often they are the mothers of our children, and that complicates things as I'm sure you know.
For some reason, men seem to be much more aware of the fact that they can be replaced than women, perhaps because they are more accustomed to there being competitors for the favors of the women in whom they are interested. Women who feel they have the upper hand seldom behave magnanimously; one need only ask women who have worked for other women to confirm that. Therefore, it may behoove the average Beta, Delta, or Gamma to occasionally act in a manner that reminds his wife/girlfriend that she is not, contra what his normal behavior indicates, his only option. Alphas and Sigmas need not bother, as their women tend to be hyperaware that their men not only have options, but know they have options.
As for Omegas, well, if she's your only option, that's all right. She probably knows she doesn't have a lot of options either.