Winning is losing
There's been research done as to what makes long-term relationships work and it's when the other person is a source of comfort to you rather than a source of competition. A lot of people are, unfortunately, brought up playing the game of winning and losing - and they bring that into their relationships. It might start off as fun banter, but it feels like one of those weather houses - if the man's out, the woman's in; if it's sunny, it can't be rainy. It's not a relationship, it's a who-is-the-best-person race, and instead of being a comfort to each other you score points off the other. That's miserable."