Victims of romance scams - the majority of whom are women - lost an average of £11,145 each last year, according to new figures.
The data, from police reporting centre Action Fraud, showed that £50m was lost in these scams in 2018 when fraudsters pretend to be romantically attached.
Fraudsters trick victims into sending money or gather enough personal information to steal their identities.
These scams of the heart are being highlighted ahead of Valentine's Day.
Police say that victims are targeted via online dating websites, apps, or through social media. Fraudsters use fake profiles to form a relationship with them.
In 2018, 4,555 reports of romance fraud were made to Action Fraud. Total losses were up by 27% compared with the previous year. The total is likely to be higher as many victims are thought to have suffered in secret.
The average age of a romance fraud victim is 50 and 63% of victims are women. They lose twice as much on average as males, Action Fraud said.
Commander Karen Baxter, head of the City of London Police's economic crime department, said: "As cases of romance fraud increase each year, so too does the cost to victims, both emotionally and financially.
"The emotional damage of falling victim to romance fraud can often be far more difficult to come to terms with."
Dating site users are being urged not to take everything at face value.
Many people who have been caught out have judged those they met online based on their social media profile, their job, or simply trusting them too soon.
Online safety advice
- Criminals who commit romance fraud trawl through profiles and piece together information such as wealth and lifestyle, in order to manipulate their victims
- Police can investigate and help to provide support, but often cannot get the money back
- It is very simple for fraudsters to cover their tracks by masking IP addresses and using unregistered phone numbers
- Never send money to someone online you have never met
- Think twice about posting personal information which could be used to manipulate or bribe you