Last week '36 questions that will make you fall in love' went viral.
Now, married couples can apparently test whether or not they are still in love by asking each other two simple things.
University of Virginia economists Leora Friedberg and Steven Stern analysed data from a relationship survey of 4,242 couples that was originally conducted in the 1980s.
The original researchers asked couples two questions:
1) How happy are you in your marriage relative to how happy you would be if you weren't in the marriage?
2) How do you think your spouse answered that question?
Participants were asked to grade their answer on a scale of 'much worse' to 'much better'.
The couples then carried on with their lives before the researchers asked them the same questions again six years later.
Perhaps unsurprisingly, Friedberg and Stern found that those who thought they would be no worse off single in the first round of questions were more likely to have broken up by the second round six years later.
What was surprising though, was that those who over-estimated their partner's happiness were even more likely to be divorced after six years, than those who simply said they might be happier unmarried.
Friedberg and Stern's research references bargaining theory - the idea that the more one spouse overestimates their partner’s happiness, the more likely he or she will bargain “too hard” and make a mistake.
Stern gave this example as an explanation: “If I believe my wife is really happy in the marriage, I might push her to do more chores or contribute a larger portion of the family income.
"If, unbeknownst to me, she’s actually just lukewarm about the marriage, or she’s got a really good-looking guy who is interested in her, she may decide those demands are the last straw, and decide a divorce would be a better option for her.”
Of the 4,242 couples, 296 (7%) were divorced after six years.
It seems the key to a happy marriage may be knowing how your partner feels about your relationship. And what's the one way to make sure you know how they really feel?
Ask them, pure and simple.