Human relationships are built on not only love but also power according to a recent report.

"You always decide where we go," she complains and he retorts, "And you always decide which movie we see." Arguments like this are normal in a relationship. They are a problem only when they are not about specific grievances, but about power.

"There's no relationship without power," noted Tanja Boeckling, a relationship counselor from Koblenz. Influence must be mutual if a relationship is to develop, she said.

In the words of the Berlin-based psychologist, Wolfgang Krueger, "It's important to be aware of these power processes and to overcome them."

"Most couples have recurring quarrels," remarked Rudolf Stross, a relationship counselor from Bergisch Gladbach. They involve mainly an exchange of resources that one partner possesses and the other lacks, Boeckling said. Classic issues are sex, money and jealousy.

"To put it bluntly, the man buys the women a dress and then she sleeps with him, for example. Or the other way around," Boeckling explained. She said an exchange of this kind was basically reciprocal in nature: "One person rewards the other for having done something nice."

The distribution of power in a relationship often has to do with who has made the greater emotional investment. "The partner with the upper hand is the one who can more easily do without the other," Krueger said, adding that women were frequently the more powerful partners nowadays.