Erotomania.
Erotomania is a type of delusion in which the affected person believes that another person is in love with him or her. During an erotomanic psychosis, the patient believes that a "secret admirer" is declaring his or her affection to the patient, often by special glances, signals, telepathy, or messages through the media. Usually the patient then returns the perceived affection by means of letters, phone calls, gifts, and visits to the confused recipient.
The term erotomania is often confused with obsessive love.
The term erotomania is often confused with obsessive love.