Couple Fights In Front Of Third Wheel – Leo and Rebecca Buzz Question

Leo and Rebecca Buzz Question - First let me say that YES, I'm the THIRD WHEEL when it comes to my buddy and his wife. I'm always hanging with them Well, something is happening a lot lately and I'm a little put off by it. They will have FULL BLOWN OUT FIGHTS in front of me. We're talking fights that couples have behind close doors. Look, I'm a single dude and don't want to get into the middle of all that. But, they will fight then ask me my opinion on whatever their fighting about. Any suggestions on how to handle???