Short answers, pulled from the story.
The word romantic love evolved from the Latin word Romanus meaning Rome into the Old French romans to describe vernacular stories of chivalry and love. This historical accident began in the Middle Ages when these romans became chivalric romances that elevated the status of women while demanding passionate suffering and separation from them.
Dopamine is produced in the ventral tegmental area of the brain and projected to the nucleus accumbens creating a motivational state that feels like an addiction. This biological definition suggests that intense feelings of being in love are adaptations that arose during the recent evolutionary history of humans and involve reward pathways mediated by oxytocin and endogenous opioids.
A 2025 survey found that 64% of people had experienced limerence and 32% found it so distressing that it was hard to enjoy life. Dorothy Tennov found that limerence may be experienced by 50% of women and 35% of men and is characterized by intrusive thoughts and constant fantasizing about the limerent object.
Romantic love is believed to have evolved in hominids about 4.4 or 2 million years ago though the exact time has not been identified yet. A 1992 cross-cultural study by William Jankowiak and Edward Fischer found that the experience of romantic or passionate love was in fact universal or near-universal documented in 88.5% of cultures.
Adversity tends to heighten romantic passion through a phenomenon called the Romeo and Juliet effect or frustration attraction where obstacles like rejection or physical separation spark interest and emotional volatility. Passionate or infatuated love thrives under the uncertainty of intermittent reinforcement in situations with only irregular meetings between lovers.
It was not until the 18th century that people began to marry for romance after marriage historically did not exist to bind couples for love or companionship. Marriage as a cultural practice may only be about 4,350 years old and its original purpose in patriarchal societies was to ensure the transfer of wealth and responsibilities to a man's true biological children.