For some reason, this thread was on my mind a lot and I was reminded of a death certificate. It lists the cause of death, for example, respiratory arrest. Then it lists one or more proximate causes. What caused the respiratory arrest? Some underlying lung disease?
It seems to me that perhaps socializing may be the cause of the divorce, but there was probably a proximate cause. As jaw22 pointed out, do they communicate? Are they really committed to each other and to their marriage? From what I’ve observed (and I am certainly no expert), people who are fully committed do not get distracted from socializing with other couples.