I suggest the phrase "win-win" describes what you are looking for; see the Cambridge Dictionary definition.
> A win-win situation or result is one that is good for everyone who is involved: >
Flexible working hours are a win-win situation for employers and employees.
And win-win implies a relationship or trade of goods or services that benefits all parties and wouldn't exist with out the relationship.
UPDATE:
Reading through the other answers, I will also add that win-win is more colloquial and avoids some of the issues raised by others.