If your boss is sharing you this much information on his personal life AND wanting you to make a decision for him...
Hmmmm
Anyways, we know nothing about asa_don's boss aside from third hand information. These assumptions are inaccurate without hard facts on the situation. OP is asking for input (which is incredibly stupid) if they were to be relayed to his boss, so this thread should be taken absolutely hypothetically for anyone's sake.
If the wife happens to cheat, it will come out eventually. Just let it happen and deal with it when it does. Don't count the eggs before they hatch and don't pine over the Christmas grinch. Be optimistic and look for good intentions in people for fvck's sake. I've been burned, you've been burned....and guess what? We have all been burned. It's always easy to look for the bad things. Easier to criticize. Easier to put down other people.
Let's all look at the positive side. Let's all look for the good in people. I sure as hell it outweighs the bad in most people. Let's keep our biases aside and give people the benefit of the doubt.
If the worst happens, she cheats on him, they get divorced and she gets the kids. So what? Life goes on and he will smarten up. Giving him any advice is planning for abortion when the chick is already knocked up. Ain't no use in crying over sh!t you can't control.