Criticism of your partner can apparently be cancelled out by five compliments, according to a German scientist.
Dr Hans-Werner Bierhoff has worked out a mathematical equation for how couples can ensure a happy relationship, ananova.com reports.
He found that couples should compliment their partners five times for each time they criticise them.
"Then people feel good in their relationship. Goodwill increases your potential to be happy," Professor Bierhoff said.
These pearls of wisdom were learnt during the professor's research for a new book, What Makes Love Strong, for which he conducted tests on thousands of individuals and couples.
He and Elke Rohmann, a colleague at the social psychology department of Ruhr University Bochum, also found that unemployment, infidelity or "stressful experiences" like diseases, depression or childbirth can cause relationship troubles.
