Next time you take a date to the movies, see a horror flick. At least if you want to stay together.

That's the advice researchers at Heriot Watt University in Edinburgh have for would-be couples.

Romantic comedies, or "rom-coms," promote unrealistic expectations of love and relationships, according to their study.

Researchers had 100 student volunteers watch the 2001 romantic comedy "Serendipity," and 100 more watch a creepy David Lynch movie.

Students watching "Serendipity" were found to be more likely to believe in fate and destiny. Fans of romantic comedies were also found to have a stronger belief in predestined love.

"Marriage counselors often see couples who believe that sex should always be perfect, and if someone is meant to be with you, then they will know what you want without you needing to communicate it," said the university's Dr. Bjarne Holmes. "We now have some emerging evidence that suggests popular media play a role in perpetuating these ideas in people's minds. The problem is that while most of us know that the idea of a perfect relationship is unrealistic, some of us are still more influenced by media portrayals than we realize."

Researchers studied 40 films between 1995 and 2005, including "You've Got Mail," "Maid In Manhattan," and "The Wedding Planner," and identified common themes in them which they believed were unrealistic.

"[These films] do capture the excitement of new relationships but they also wrongly suggest that trust and committed love exist from the moment people meet," said Kimberly Johnson, who also worked on the study "Whereas these are qualities that normally take years to develop."

Go to BBC.co.uk for the full report.