Conversely, if someone says to you: "if you love me, you would...," that is not love, says Dr. Northrup.

‘There’s a notion of destiny and couples in romantic comedies immediately understand each other,’ said Dr Holmes. ‘If you think that’s how things are, you are setting yourself up to be disappointed.

As part of their research, Dr Holmes' team had around 130 student volunteers watch the 2001 romantic comedy Serendipity, while another group of the same size watched a David Lynch drama.