You’ve probably known a couple who just can’t seem to make things stick, you know? They’re together, they’re apart, they make up, they split up, and all the while, they seem to generally get along. They seem like a good match, but there’s something… some important piece of the puzzle, that’s missing or that they can’t get a good grip on. Eventually, they split up for keeps, often amicably, and friends and family are left scratching their heads.