Viral videos might sound like fun but for one poor fiancee, it means catching her soon-to-be-husband in the act.

A 31-year-old man allegedly part of a randy couple appearing to have sex in front of other passengers on a Ryanair flight might not have wanted the viral video being seen by quite so many people.

Friends of the man told The Sun that the woman in the video was "just a random woman" who he did not know before that day, and that his 25-year-old fiancee was back home and "heavily pregnant".

Other passengers on the Ibiza-bound flight told reporters that the man in the video called out "anyone got a jelly?", a term for a condom, before the woman took off her underwear. Some passengers reportedly laughed at the situation while others complained to staff who allegedly failed to act.

"He doesn't seem to be too bothered he has left his six-months pregnant wife-to-be at home while he cavorts with random strangers," the friend told the newspaper, while his step-father said he had seen the video but not yet spoken to his step-son.

At the time, Ryanair said they were looking into the matter and would not tolerate "unruly, disruptive or inappropriate behaviour".