What if you were to hold up a picture of your wife and look at her as you receive the happy ending? This could not possibly be considered cheating.
I assume you mean my gf Vivi? No, I wouldnt, as long as it was only a finger, who cares? His answer in the 1st page.
He's free to do whatever he wants. I think, when you have kids, the landscape probably changes. But if it's just you and a SO, I don't see the harm in getting "gratification" outside the relationship.