When we experience Romantic Feelings, a Crush or are Falling in Love with someone, it change your brain chemistry in a big way. How strong your romantic feelings are, or crush, is determined by the strength of your brain's response.
When you start experiencing romantic feelings for someone, get a crush or start falling in love, dopamine levels in your brain shoot up, causing a release of endorphins, the hormones that generate feelings of euphoria, happiness, joy and ecstasy. You can get huge surges of energy, euphoria and exhilaration, due to a high release of endorphins.
Beside the rush of endorphins, high levels of dopamine suppress the calming and sensible influence of serotonin, another neurochemical that influences mood. In normal doses, serotonin is the antidote to stress; the chemical that calms and relaxes us. But when the brain is drenched in dopamine, serotonin is silenced.
The silence of serotonin serves genetic pur