It should come as no surprise that having intercourse is a positive expression of a love’s intensity. People in love are more likely to have sex with each other on a regular basis. The O’Leary study showed, however, that part of the reason for the positive association between sex and love is that people who are happiest in their relationships both love their partners more and have sex more frequently. Whatever the cause, the point is that sexual activity builds and maintains feelings of love and even happiness that endure over time.
