Excuse my random Wiki moment.

The triangular theory of love is a theory of love developed by psychologist Robert Sternberg. The theory characterizes love within the context of interpersonal relationships by three different components:

1. Intimacy – Which encompasses feelings of closeness, connectedness, and bondedness.
2. Passion – Which encompasses drives that lead to romance, physical attraction, and sexual consummation.
3. Commitment – Which encompasses, in the short term, the decision to remain with another, and in the long term, the shared achievements and plans made with that other.

The “amount” of love one experiences depends on the absolute strength of these three components; the “type” of love one experiences depends on their strengths relative to each other. Different stages and types of love can be explained as different combinations of these three elements; for example, the relative emphasis of each component changes over time as an adult romantic relationship develops. A relationship based on a single element is less likely to survive than one based on two or three elements.