As the virtual world steps up to a new level with the launch of Second Life which allows people to make a virtual character in their own image and conduct all aspects of life, there is concern about what this will do to real-life relationships.
Research by Spunlogic, an interactive marketing company, conducted a survey into the effect of Second Life on relationships.
It encountered an example of a married man who had got married in the virtual world.
This, according to researchers, raised questions about his fidelity.
Shelby Majors, a researcher on the survey, said: "These results explain the recent debate about whether a man's wife should have filed for divorce after he married another woman in a virtual world."
Just 58 per cent of respondents in the survey believed interactions in the virtual world could be classified as infidelity, but this number was lower for men and also for young people.
Dr Melissa Read, director of behavioural research at Spunlogic, said: "Infidelity, a behaviour normally deemed unacceptable in human-human interaction, becomes more acceptable when interactions are mediated by various technologies.
"What other socially inappropriate behaviours might be perceived as acceptable when produced in technology-mediated interactions? And, more importantly, why?"