When a couple has chemistry, they usually have it both figuratively and literally. Behind those sweaty palms, thumping heart, stomach in knots, and nervous jitters is the physiology of love. Such sensations often mark the first stage of a romantic relationship, called limerence.
However, post-honeymoon period (anywhere from eighteen months to four years), our chemistry transforms the physical manifestation of love into a different form. In stable, long-term relationships that have reached the secure attachment phase, many people experience a warm, comfortable feeling of security. Attachment love hormones are more comparable to morphine than the cocaine-like high of limerence.
Phenylethylamine and Dopamine
Tolerance for the Love Drug
Many scientists believe that after a limerence, typically anywhere from 18 months to 4 years, your body becomes accustomed to those energizing love drugs. Just like you build a tolerance to alcohol, your limbic system adapts to the formerly cocaine-like neurochemical state. In this secure phase of the relationship, your brain produces endorphins, opiates more like morphine than speed. "Unlike PEA, [these endorphins] calm the mind, kill pain, and reduce anxiety," Dr. Fisher explains.