Should you marry her?

Before you pop the question, pre-proposal professionals reveal how you can tell if she's really the one

Ignore the first four or five

says Professor Bruce Brown, a mathematician at the University of New South Wales

It’s not the most romantic way to think of her, but your girlfriend is a random variable in the happiness equation that is your life, says Professor Brown. “Don’t commit to the first 37% of women you get involved with. Then propose to the very next one who is better than all the previous.” The average British male has 12.7 sexual partners over a life time so, if you trust the maths, the first four or five are out. This is based on an ‘optimal stopping’ formula, which calculates when to take a particular action in order to maximise your reward. Use Professor Brown’s formula to work out if you’re ready to propose... Choose the oldest age by which you want to marry (n). Select the age you’d settle down if the girl was right (p). Calculate: n–(px0.368) to find your optimal proposal age.

A good, feisty business partner makes a good wife

says Jean Smith, an anthropologist who specialises in dating and flirting

“Couples that last evaluate each other not as lovers but as potential business partners,” says Smith. “Would you let her make decisions on your behalf? Do you trust her not to let feelings mar her judgement? Do you share a vision for the future?” Answer these questions after 12-18 months when your judgement isn’t clouded by the first flushes of love. Then check your fighting style. Studies have found that couples who clash often are more content, have better sex, and stay together for longer.

If she fights your corner and gossips, marry her

says Dr Jo Setchell, a primatologist at Durham University

“Few primates pair-bond for life,” warns Setchell, whose studies of apes and monkeys offer hints on whether a potential fiancée will push your evolutionary buttons. “But committed Titi monkeys chase off threats to their male and will abandon personal rewards – like food or shelter – to pursue a mate.”

If your girl fights your corner now – whether it’s standing up for you to snarky friends or being supportive when you work late, you’ve got a loyal ally for life. “Bonded primates also groom each other. Recent research suggests that the human equivalent of grooming has evolved into gossip. If she wants to share hers with you – and vice versa – signs point to mutual commitment.”

Be happy to spend time apart

says Amanda McAlister, head of family law at solicitors Russell, Jones & Walker

“The early signs that predict a doomed marriage are common,” says McAlister, who has 13 years’ experience of what underpins marital success or failure. “A loyal spouse won’t begrudge hobbies or anything you do in your own time. If she does, it’s the number one marriage wrecker.” Look out for telltale eye rolls when you make ‘me-time’ plans. Research from the Gottman Relationship Institute in Seattle found this was one of the most reliable divorce predictors. McAlister also cites any whiff of pressure to marry as a major ‘Divorce Approaching’ sign. “Whether it’s from her, your family or Beyoncé, if you’re pressured into putting a ring on it – you shouldn’t do it.”

A two-year age gap and you're good to wed

says Karen Gask, senior research officer for the Office of National Statistics

“Think of statistics as the entire country giving your marriage a test-run,” says Gask. First, are you both earning professionals? Your marriage is nearly 50% more likely to last than couples who aren’t. Men aged 30-34 on their wedding day see the greatest marriage success. Outside that age, your outlook is favourable if your wife-to-be is of a similar vintage. “For every year in age difference greater than two years, the odds of staying together decreases by 5%,” Gask says. Other studies indicate that if her parents split, she’s twice as likely to divorce you. Finally, first-timers are 62% more likely to stay together than those who are re-marrying.