A relationship involves two very different people bringing two sets of values, cultures and environmental influences together. They also have two sets of goals and desires.
It's trivial enough to observe that when partners act more often in cooperation with the other partner's goals and less in line with their own selfish goals, both people are more happy. Not ground-breaking, but the devil is in the detail they say.
Hal Kelley and John Thibaut proposed that partners have two major forms of control over their partners. They called these 'fate control' and 'behaviour control'.
Behaviour control is fairly straight forward. We can easily influence each other's behaviour by letting our friends and partners whether we approve of their behaviour or not.
Fate control is when one person acts in such a way that the other person, or people, have no say over the decision. This sounds problematic, but can often be quite positive, like throwing a surprise party or taking the trash out on their behalf. But, unsurprisingly, when fate control is pervasive in a relationship it causes problems. If it happens too often, the other person may start to feel out of control and in doing so, begin to feel dissatisfied.
What's critical to note is that both behaviour control and fate control are unavoidable aspects of a relationship. There is no sensible pairing of people that doesn't involve communication about preferences, or indeed one person making decisions on behalf of the other.
But beyond these pragmatic concerns, we, each of us, have an underlying need for control. A need to feel that our relationship and its future lies in our hands even though we have given up some part of it to those we care about.
And here is where we return to where we started---the overlap between our own goals and the goals of those over whom we share control.
Interdependence theory tells us that relationships are an iterative process of 'meshing' our goals with the goals of those we care about. We find gym buddies, and motivate one another. We find friends who share our interests, and spend time indulging ourselves with them. We find those who share our vision of the future, and start our most intimate kinds of relationships. In each case, we are matching our goals with the goals of others.
When fate control and behaviour control are organised around these shared goals more often than they are organised around those goals that belong to us alone, we are far more likely to succeed in the relationship.
We must control others, not for our own sake, but for theirs too. And somehow that menacing sentence is a necessary feature of our relationships.