This is exactly why my group does not allow couples to play in our group. Every single time we've had a couple in our group, there has been some instance of preferential treatment. No matter if its DM to player or player to player!
An interesting aside to this, I DM two groups right now, and one table consists of three couples and the other two couples. It works great, they always know where each other are and no one is ever too busy with the other to not make a game!
