Never understood why it's the single woman who gets the blame when there is an affair.
Take Kristina and Ben (as Terry has brought her up) she wasn't the one who made a commitment to Bens wife nor is Kristina the one who chose to have children with her, Ben did. Ben could have walked away, asked for a chaperone or done a million other things if he felt not capable of being faithful but he did none of those things. What he did and chose to do was lie to his wife, that is not Kristinas fault, that is Bens.
If you are married or in a relationship then it is down to you and you alone not to have an affair and if you do then that too is down to you.
As for DoD, if his word is to be believed then he has everything he could ever want with his wife so why would he cheat.