Love alone is no predictor of longevity in a relationship. And it is not always the ones we love the deepest who we end up spending our lives with.
The enigmatic nature of love – what sparks and explodes our hearts and what sustains them over a lifetime – remains a puzzle for philosophers and scientists.
More than 320 couples a day get married in Australia. About three in 10 will remain in healthy, happy marriages, according to psychologist Ty Tashiro in his book The Science of Happily Ever After.
Now, in an effort to calculate the algorithm of lasting love, two scientists believe they have found "rare empirical evidence" of it. Or at least the questions that will determine whether we are in love and whether our relationship is likely to last.
The questions are: How happy are you in your marriage relative to how happy you would be if you weren't in the marriage?' and 'How do you think your spouse answered that question?'
The study, published in the current issue of the International Economic Review, tracked how 4242 couples answered these questions six years ago.
Only 40.9 per cent of couples accurately identified how their spouse would respond.
This left almost 60 per cent of couples with mismatching responses and about one-quarter of these with "serious" discrepancies in overall happiness.
Not knowing how their partner felt about their relationship was just one part of the problem, the researchers from the University of Virginia said.
Miscalculating can lead to inadvertently pushing your partner over their limit and result in a split.
"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," explained co-author of the study, Steven Stern.
"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."
That said, even among couples who weren't happy, or misjudged their partner's answer, the algorithm and divorce rate didn't always match.
This is because, the authors hypothesise, we often care and will work at it regardless.
"The idea of love here is that you get some happiness from your spouse simply being happy," the study's other author, Leora Friedberg said. "For instance, I might agree to do more house chores, which reduces my personal happiness somewhat, but I get some offsetting happiness simply knowing that my partner benefits."
Interestingly, separate research has also deduced two factors that predict whether the flame will stay alight forever.
In this instance, it isn't questions but traits that are key to unlocking our hearts long-term.
Those who compliment their partners, and seek constructive ways to overcome obstacles together, remained tight. These couples are, what the researchers refer to as, 'Masters of Love'.
Those who criticise their partners and see only obstacles, on the other hand, became unstuck. These couples are, what can be referred to as, the 'Disasters of Love'.
"There's a habit of mind that the masters have," researcher John Gottman has explained, "which is this: they are scanning their social environment for things they can appreciate and say thank you for.
"They are building this culture of respect and appreciation very purposefully. Disasters are scanning the social environment for partners' mistakes."
What these contrasting traits reveal is whether or not we bring kindness and generosity or contempt and criticism to our relationship.
Researchers found contempt is the top trait tearing couples apart.
"It's not just scanning the environment," added John's wife and fellow researcher, Julie Gottman. "It's scanning the partner for what the partner is doing right or scanning him for what he's doing wrong and criticising versus respecting him and expressing appreciation."
This appreciation and respect extends to fights the Gottmans say.
"Kindness doesn't mean that we don't express our anger," Julie Gottman explained, "but the kindness informs how we choose to express the anger. You can throw spears at your partner. Or you can explain why you're hurt and angry, and that's the kinder path."
Love can be as fickle and fragile as it is powerful and enduring.
Science cannot surmise its intricacies. But, certainly, research can use data to paint us a picture and help us master the art of love so we can be a better partner in our partnerships. It can guide us towards seeing ourselves and our partner with greater clarity and kindness so that we can last the distance with our heart intact.
