According to psychologist Elaine Hatfield and her colleagues, there are two basic types of love: compassionate love and passionate love. Compassionate love is characterized by mutual respect, attachment, affection and trust. Compassionate love usually develops out of feelings of mutual understanding and shared respect for one another.
Passionate love is characterized by intense emotions, sexual attraction, anxiety and affection. When these intense emotions are reciprocated, people feel elated and fulfilled. Unreciprocated love leads to feelings of despondence and despair. Hatfield suggests that passionate love is transitory, usually lasting between 6 and 30 months.
Hatfield also suggests that passionate love arises when cultural expectations encourage falling in love, when the person meets your preconceived ideas of an ideal love, and when you experience heightened physiological arousal in the presence of the other person.
Ideally, passionate love then leads to compassionate love, which is far more enduring. While most people desire relationships that combine the security and stability of compassionate with the intensity of passionate love, Hatfield believes that this is rare.