There are so many big issues that put pressure on a couple that it seems silly to squander your chances on the little stuff.
Over time, seemingly trivial things - such as responding half-heartedly to your partner's good news, or spending too much time on the phone - can have a corrosive effect on long-term unions, causing fractures in what could be a perfectly happy match.
But unlike life-changing events such as infidelity or time spent apart, these minor habits are easy to fix.
We take a look at five common modes of behaviour that have been scientifically proven to cause trouble in a relationship, and how best to avoid them:
Lack of enthusiasm
How we respond to our partners on a day-to-day basis - even in little, incidental remarks and exchanges - makes a big difference to the happiness of our relationships over a long-term period. US psychologist John Gottman has spent decades studying the dynamic of couples in order to work out the science behind maintaining a loving bond. In one observation session with 130 newlyweds, he looked at "bidding interactions" between couples, whereby one person would bid for their partner's attention with a throwaway remark ("look at that beautiful bird outside!")
These bidding interactions happened almost constantly, he noted, and people would either respond positively by "turning toward" (actively supporting and showing interest in the bid) or "turning away" (ignoring the bid, or giving a hostile response - "I'm just in the middle of something right now"). These interactions may seem minor or silly, but in a follow-up six years later, Gottman identified that those who had divorced had logged a 33% "turning toward" rate in the initial study. This is in comparison to the couples who were still together, who logged a 87% "turning toward" rate.
"If your partner expresses a need," explains John's co-researcher and wife Julie Gottman, "and you are tired, stressed, or distracted, then the generous spirit comes in when a partner makes a bid, and you still turn toward your partner."
In a similar study from 2006, psychological researcher Shelly Gable found that couples who lasted the distance were the ones who used "active constructive" reactions to one another's good news ("That’s great! Congratulations!"). This was opposed to passive constructive ("But are you sure you'll be able to cope?"), passive destructive (acknowledging the news in a half-hearted way) or active destructive (ignoring the news). All of these latter reactions prompted bad news for the long-term prospects of those involved, she found.
Craving money and material things
Are you and your partner forever hankering after a slick new car or that expensive vintage-grey sofa from Made? It could be a worrying sign. A 2011 study published in the Journal of Couple & Relationship Therapy found a connection between high levels of materialism and unhappy marriages. In the survey of 1,700 couples, those who had higher materialist desires experienced lower marital quality, even where they were united in their materialist values.
That's added to a wide-ranging 2006 Princeton survey which found that spending money on "things" left people feeling emotionally flat, and that couples who viewed money as unimportant had healthier relationships than those who prized it.
Lead author and psychologist Graham Hill said people should focus on shared experiences, such as a road trip or pub drinks, to promote enduring happiness.
"We don't tend to get bored of happy memories like we do with a material object," he noted.
Ambiguity over shared household chores
It's hardly front-page news that housework can be the source of enormous conflict between couples. And it's amazing how quickly leaving the toilet seat up or not washing the dishes can lead to the most almighty of rows. A 2007 Pew Research Poll found that division of domestic chores was among the top three issues associated with a happy marriage, second only to faithfulness and a good sex life.
What's interesting here is that research has shown it's not who does the housework per se, but the lack of a good system that really kicks things off. Between 2001 and 2004, a team of UCLA researchers tracked the lives of 32 dual-earning middle-class families living in Los Angeles. The couples who lacked clarity on what, when, and how household tasks and responsibilities would be carried out ended up feeling the most dissatisfied with one another.
They reported feeling drained and rushed, and had difficulty communicating their dissatisfaction in their lives. This compared to those couples who had a clear understanding of one another's roles and tasks, who did not spend as much time negotiating responsibilities, with daily lives that seemed to flow more smoothly.
"Conflict was more prevalent when couples had not worked out a clear division of labour in the home and had to renegotiate responsibilities from one day to the next," the researchers conclude. "Ambiguous models appeared to provide ample opportunity for partners to express displeasure toward one another."
Spending too much time on your phone
We've all experienced that flash of irritation when a partner looks at their phone during a dinner date, so it comes as no surprise that phone use can chip away at the intimacy of a long-term relationship. A study last year found that smartphones can often end up being the "third wheel" of a sponsored_longform, with 75% of women questioned claiming that they reduce the amount of time spent with their other halves, and interfere with their love lives. A quarter said they were annoyed after their partner had fired off a text during an important conversation, according to the survey published in the journal Psychology of Popular Media Culture.
"This is likely a circular process that people become trapped in, where allowing technology to interfere, even in small ways, in one's relationship at least sometimes causes conflict, which can begin to slowly erode the quality of their relationship," says lead author Brandon McDaniel of The Pennsylvania State University.
Co-author Sarah Coyne adds that, "by allowing technology to interfere with or interrupt conversations, activities, and time with romantic partners - even when unintentional or for brief moments - individuals may be sending implicit messages about what they value most, leading to conflict and negative outcomes in personal life and relationships."
She recommends putting your phone on silent; "If you need to check on something legitimately important, provide an explanation first and then check your phone," she says. "Finally, don’t get defensive if your partner expresses disdain at your constant texting or gaming – it’s somebody’s way of saying they’d like to connect with you in-person."
The negative effects of sleep deprivation are well documented but a 2013 study from University of California, Berkeley found a surprisingly specific link between poor sleep and lack of appreciation and gratitude between couples in long-term relationships.
More than 60 couples aged 18 to 56 were videotaped engaging in problem-solving tasks, as well as keeping sleep diaries and writing down what they valued about their partners every day. Researchers identified a clear decline in levels of gratitude that was associated with poor sleep. People were more likely to report feelings of selfishness after a night of sleeping poorly and demonstrated less of a sense of appreciation of their partners, compared to those with better sleep quality and sleep quantity. What's more, participants tended to feel less appreciated by their partners if either they or their partner slept poorly.
The results indicate just how strongly a good night's sleep can influence the emotional dynamic of a relationship.
"Poor sleep may make us more selfish as we prioritize our own needs over our partner’s,” said Amie Gordon, a lead investigator of the study. "You may have slept like a baby, but if your partner didn’t, you’ll probably both end up grouchy."
"Make sure to say to say ‘thanks’ when your partner does something nice. Let them know you appreciate them."
Words: Anna Brech, Photos: Rex Features and Getty Images
What do you think? What are the habits that lead to relationship disaster, in your experience? How can things be improved for a happier dynamic? Let us know in the comments section below