The one where one party isn’t abusive/ cruel/evil, but is just your bog standard simply dreadful. Yet their significant other is a total poppet and somewhat unassuming and nice.
You know the ones? Where you find yourself at events where they are and spend your time considering rehoming and rehabilitating the nice one and then relocating them 3000 miles away and releasing them back into the wild to start a new life with a suitable mate?