But, the more I thought about it, that's not how it works, for many of my friends in relationships. Many of them are cuddly and affectionate with their friends, but restrict some of their more pugnacious activities to their special ones. Aside from a few special activities (e.g. kissing), it's the opposite of common wisdom. I know fizzygeek and I cheerfully trade punches we generally wouldn't inflict on anybody else. The old quote "Why do lovers do this to each other? Because no one else would put up with it!" rings true. Even in popular media, what do good friends do? They punch each other in the arm.
Now don't get me wrong, I'm not confusing any of this with an abusive relationship. I'm just amused that among my acquaintences, sharing physical intimacy doesn't connote more than simple affection, but friendly violence is restricted to lovers.