Love is a mental illness, narcotic psychosis of a paranoid type on a sexual basis. In the acute phase (falling in love) is caused by amphetamine addiction, in the chronic - by endorphin. Paranoid symptoms are most vividly manifested in the acute phase: delirium of an overvalued idea, loss of adequacy of perception, inability to critically evaluate the object of love (often associated with aggression against attempts to give such an assessment) while maintaining the ability to reason sensibly on abstract topics, emotional instability, etc. Like other paranoid disorders, it occurs more often at a young age and proceeds with spring-autumn exacerbations.
The chronic phase is often called "true love" and is opposed to the acute one, although in fact these are two forms of the same disease. Although the chronic phase usually outwardly proceeds more calmly than the acute one, this is the calmness of the addict who regularly receives his dose of the drug: if problems arise with the dose (suspicion of treason, etc.), and the withdrawal syndrome awakens no less, and sometimes more violent passion than in the acute phase.