Psychologists say that "lovesickness" is a genuine disease that needs more awareness and diagnosis.
And those little actions that are normally seen as symptoms of the first flush of love - buying presents, waiting by the phone for a call or making a bit of an effort before a date - may actually be signs of deep-rooted problems to come.
Frank Tallis, a clinical psychologist in London, examined the historical attitudes to love and mental illness, stretching back to the time of the ancient Greeks.
Before the 18th century, lovesickness had for thousands of years been accepted a recognised ailment. But for the past 200 years it has been out of favour with medical practitioners as a proper diagnosis, Dr Tallis said in a report in The Psychologist magazine.
Dr Tallis said modern research suggested that the effects of being lovesick could be described in the latest diagnostic terms.
Symptoms can include mania, such as an elevated mood and inflated self-esteem, or depression, revealing itself as tearfulness and insomnia.
Aspects of obsessive compulsive disorder can also be found in those experiencing lovesickness, such as preoccupation and obsessively checking for text messages and e-mails.
"The average clinical psychologist will not receive referral letters from GPs and psychiatrists mentioning lovesickness," Dr Tallis said. "However, careful examination of the sanitised language will reveal that lovesickness may well be the underlying problem.
"Many people are referred for help who cannot cope with the intensity of love, have been destabilised by falling in love, or who suffer on account of their love being unrequited."
A consequence of this might be a suicide attempt - dramatising the ancient contention that love can be fatal, Dr Tallis said.
"Although there is much modern research into the treatment of relationship and psychosexual problems, there is little dealing with the specific problem of lovesickness," he said.
"Perhaps now is the time for us to take it more seriously and take a lead from those ancient clinicians who diagnosed and treated it like any other complaint."
Professor Alex Gardner, a clinical psychologist in Glasgow and a member of the British Psychological Society, said doctors needed to be more aware of lovesickness as a possible diagnosis in their patients. "People can die from a broken heart," he said. "Lovesickness is probably extremely common."