Do two football teams meeting in a game, ever, ever like each other? I mean, for years I’ve been hearing variations of These two teams don’t like each other! in the pre-game blather.
Has anyone ever seen a player not make a tackle ot hard hit, or not pick up a fumble, because it turns out they liked the other team?
I submit the probability that, at least in the NFL, most of the players know each other well and perhaps regard themselves as friends. I think there are few players who hate each other. On the contrary, it is entirely likely that the players, in general, consider each other respected colleagues and are probably quite friendly with each other.
They are, however, professionals at what they do, and would probably not seriously consider holding back against players on other teams. In particular, I believe they train hard, and don’t hold back against their teammates they train against.