I'm prepared to cut Victoria and Derrick a break.
Victoria's playing a card that will get her further in the game by snuggling up to the alpha dog. It's sleazy, but it's not bad gameplay. It isn't her job to mind Derrick's vows or to ensure that he doesn't step over whatever line of allow ability that he and his wife have worked out. It should also be noted that he laid his head in her lap, her playing with his hair is not that big of a deal.
Derrick's basically playing the same game here as Victoria. It's the classic meaningless flirtation/showmance. I wonder if he hadn't already cleared such behavior with his wife. As I recall, his bio had him doing undercover police work, so he MK doubt has had the 'what happens undercover stays undercover' talk with his wife. From there, it's not too big of a stretch to think that they have an agreement regarding in-house flirtations.
I wouldn't have either of these idiots around my family, but they are playing the game.