The idea that one develops relationships with people who are approximately as attractive as they are is called the hypothesis.

The correct answer is The Matching Hypothesis

Developed by Walster and Walster in the late 1960's, the theory says that in general we tend to assess our own desirability based on other people's views or opinions of ourselves. This leads us to prefer or seek out partners that would match our own social desirability.

Their theory states that this reasoning leads us to believe that such choices increase our chances of success while minimizing our chances for rejection and therefore, failure in the social arena.