Robert Sternberg developed a triangular theory of love at the end of the 20th century. It proposes three essential components of love that may be combined in different ways to produce eight types of love. Three basic components of love are intimacy, passion, and decision or commitment. Intimacy is defined by Sternberg as a feeling of closeness and connectedness.
Passion concerns the feelings that lead to physical attraction and romance, while the decision is about the decision that a person loves someone else and, in the long-term perspective, commitment to these relationships. The quality and length of romantic relationships depend on the amount of each component in them.
Thus, short-term relationships are guided mostly by passion than by intimacy, which plays a medium role in them, or by the decision that often plays no part in them. At the same time, long-term relationships are based primarily on decision and intimacy, while passion may be out of attention focus in them. Moreover, the components might change during the lifetime of a relationship, meaning that one of the elements might ebb. However, this only means that partners will have to work on reviving the element.