I think that the wife fucking other men does wonders for a relationship. I am not a sissy-cuck, so I am only guessing, but I think that for a sissy-cuck, the humiliation of being married to a whore is satisfying on some level. For us hotwife/stag-vixen couples, I think that it is more about instilling a sense of competition.
We know that our wives are sluts/whores and we like them that way. We know that they get hit on all the time by other men and they are likely to accept an invitation to fuck anytime. For me and other husbands like me that we know, it makes us more attentive husbands. I think that we try harder to stay in shape, to be well dressed and well-groomed, and to try harder to please the wife sexually.
I do not respond that way out of fear of losing Kate, I just don't want her to lose interest in having sex with me because she has sex so often with men who are younger, better looking, more muscular, have a bigger cock, and might be better in bed.