the theory of selecting a mate based on nearness is called
Propinquity It refers to the physical or psychological proximity between people. Propinquity can mean physical proximity, a kinship between people, or a similarity in nature between things ("like-attracts-like"). Two people living on the same floor of a building, for example, have a higher propinquity than those living on different floors, just as two people with similar political beliefs possess a higher propinquity than those whose beliefs strongly differ. Propinquity is also one of the factors, set out by Jeremy Bentham, used to measure the amount of (utilitarian) pleasure in a method known as felicific calculus.