We all know that couple — the one who doesn't care about PDA, who finishes each other's sentences, and wears matching outfits. They look so in sync and put together, and even restore our faith in love. But researchers at Washington University in St. Louis suggest "the perfect couple" may not be happy as they appear, and they may not even know it.

Happier couples tend to "underestimate how often a partner is suppressing emotions and to overestimate a partner's ability to see the bright side of an issue that might otherwise spark negative emotions," said Lameese Eldesouky, lead author of the study and a doctoral student in Psychological and Brain Sciences at Washington University, in a statement.

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Previous research has found seeing your partner through rose-tinted glasses is the secret to a healthy relationship. Partners feel happier when their spouse or partner has a more positive view of them than themselves. Similarities and viewing partners positively appear to help promote marriage satisfaction.

Eldesouky and her colleagues believe viewing partners in a positive light could blind couples from being able to read each other's emotions.

In the new study, published in the Journal of Personality, the researchers focused on two coping mechanisms used to deal with stress: expressive suppression (hiding your emotions by being calm, cool, and collected) and cognitive reappraisal (looking at the bright side of a bad situation). A total of 120 heterosexual couples, ranging in age from 18 to 25 years, attending colleges in Northern California completed questionnaires and interviews based on emotions, expressing emotions, and relationship quality. Each couple had been dating exclusively for more than six months, with some as long as four years.

The findings revealed couples were more likely to pick up on obvious, physical cues that their partner is hiding something via suppression, but not with cognitive reappraisal. Women were more likely to see their partners in a more positive light than men, overestimating their partners' ability to look at the bright side. Meanwhile, partners thought if their significant other was more emotional, they were less likely to hide feelings. Someone who expresses positive emotions, such as happiness, were believed to use reappraisal more than they actually do.

"This study suggests that suppression might be easier to judge than reappraisal because suppression provides more external cues, such as appearing stoic," said Tammy English, co-author of the study, in a statement.

These findings suggest someone who seems generally happy all the time doesn't always see things this way. The "happy couple" may be dating for years, but they need to better connect to really know how their partner is feeling.

Below are four hacks to better connect with your partner, and decode their love language.

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Work Out Together

A couple who sweats together, stays together. Exercise is known to induce symptoms of physiological arousal, such as sweaty hands, a racing pulse, and a shortness of breath, which mirror the thrill of romantic attraction. A study in the Journal of Personality and Social Psychology found people can easily mistake the two and wrongly assign physical arousal for romantic attraction. Working out with your partner will most likely boost your attractiveness in their eyes, and strengthen your body, and emotional connection.

Write Love Notes

Writing down your feelings with a pen and paper can lead to a boost in happiness and satisfaction in relationships. A study in the Journal of Writing Research found participants were able to reach a level of emotion that they could not experience through simple conversation. A nice love note will not only let your partner know how you feel, but also encourage them to open up to you too.

Read The Same Book

A way to get creative and connect together is through reading the same book. Psychologists say reading can bring partners closer together, because it gets them talking about things that are actually interesting. People can grow closer to one another by sharing their new thoughts, ideas, and fantasies with each other, which can be facilitated by reading a book.

Cook Together

Cooking in the kitchen together can leave you caught in the heat of the moment. A 2007 survey conducted by the Pew Research Center found sharing household duties can help couples stay together. Sharing household chores was in the top three highest-ranking issues associated with a successful marriage—third only to faithfulness and good sex. In the survey, 62 percent of adults said that sharing household chores is very important to marital success. Getting down and dirty to do the dishes could be a fun way to do chores and keep your relationship strong.

Source: Lameese Eldesouky, Tammy English, James J. Gross. Out of Sight, Out of Mind? Accuracy and Bias in Emotion Regulation Trait Judgments. Journal of Personality. 2016.

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