Other forms: mutualities
Mutuality is a positive, interactive relationship between people. The mutuality between you and your co-workers at the ice cream shop means there's good communication and a sense of understanding.
You could also use the term reciprocity or cooperation instead of mutuality. There's an inherent sense of give-and-take or respect when there's mutuality in a relationship. The word comes from mutual and its original definition, "given and received in a reciprocal way." If you have a relationship that works well, whether it's with your favorite teacher or your best friend, it's undoubtedly because of mutuality.