All happy families are alike; each unhappy family is unhappy in its own way.
The same could be said of marriages.Unfair to condemn when you do not know the participants.
I am always astonished when I hear about the betrayed spouse in a long-standing marriage who claims to have no idea the partner was involved in an affair. As the ex-wife of a serial adulterer I always knew, fought it until finally I gave up.
But there are all sorts of marriages. I knew a group of women where the main topic of conversation was running their husbands down and how they were 'not putting up with that any more, I'd rather have a cup of tea and my bed to myself', (always the master bedroom I noticed) The husbands all seemed decent, kindly men who provided well for their non-working wives and their dogs and their horses and cars and never appeared to seek consolation elsewhere.
Only one wife separated, devastating her husband and children, then discovered unmarried life was, and is, very lonely.
So perhaps there is a reason for this particular man's infidelity; perhaps his wife does know, but doesn't care.