aka reciprocal altruism.
As I've aged, I've embraced transactional relationships.
My metaphor is "playing catch". Toss the ball, hope your partner tosses it back. Repeat. The goal is to keep the game going.
Some one doesn't throw the ball back, oh well, move on to next partner.
Works remarkably well for children, lovers, coworkers, grocery store checkers, and every other relationship in my life.