Well, if you aren't aware that they fight like that because its for fun or because it actually deepens their relationship as they're able to hash out disagreements or differences and come to some kind of understanding or agreement, I'm not sure a normal person would think everything's okay. I wouldn't, at least.

(of course, I'm not of a mindstate where I can take something like that serious yet not serious; serious enough to spar and make a good go at it, but not serious enough to actually be affected at the end of the day. Guess I'm weak, then.)