Try to please each other, even when the boss isn't watching. You will be rewarded for any good things you do, whichever side of the relationship you are on. . . It sounds like pretty good labor relations, to me. We have all seen situations where a relationship has become warped, where it becomes one-sided. Marriages break down.
Family relationships become abusive.
The relationship between the worker and the employer goes sour. In this passage, Paul is talking about balance. Paul is talking about healthy relationships. We all know that there are times when relationships fall apart. In that case, the rules change.