Do atheists believe in the existence of friendship?

[KerimF]

Well said. But I wonder what 'evidence' in this case could be, to you in the least.

Human relationships, including friendship, consist of giving and taking. And it goes back from mutual grooming in primates to helping a friend move.

So if you have a friend, you usually help him with problems and he helps you. But if it comes down to you only helping him while he never helps you, then you feel used and you don't feel like that person is your friend, and that is because humans have sensitive antennae for detecting violations of reciprocity.

So far, friendship is about helping each other.
Is this enough?!
For example, the members of a sportive team also help each other to win in their games, does this make them a team of friends besides being a professional sportive team?