What do studies say about similarity in couples?
Imagine that we select 200 romantic partners and then mix them up so that new partners are randomly assigned. According to research, if you look at the similarity between the members of romantic couples and compare it to that of the two people who got together randomly, couples in real relationships tend to be more similar to each other than randomly matched couples.
But knowing that couples tend to be similar doesn’t necessarily mean that similarity matters. Just because couples tend to be similar does not mean that more similar couples have more satisfying relationships or that their relationships last longer. Perhaps couples who are different are less common but just as satisfied and successful.
What we know about the similarity and prosperity of relationships is that similarity can matter, but researchers have shown that similarity in couples tends to be more about shared values and backgrounds, such as their social class and religion.
And these are the factors that seem to predict the success of the relationship. Couples with more similar attitudes, values, and backgrounds tend to experience longer-lasting satisfaction, companionship, intimacy, and love, and are less likely to break up.
Connection between similar personalities and the prosperity of a relationship
Similarity in personality, on the other hand, doesn’t seem to matter as much. While some research found that people report being more attracted to people with similar personalities, similar personalities did not accurately predict relationship outcomes.
The similarity of the couples may depend on how they met. A cross-sectional study of 137 married or cohabiting heterosexual couples found that couples who “fell in love at first sight” were less similar than couples who were first friends. Particularly at the levels of extraversion, emotional stability and autonomy.
However, contrary to the researchers’ hypothesis, couples who “fell in love at first sight” did not report having a lower-quality relationship. Which suggests that their differing personalities weren’t necessarily a burden on the relationship .
While similarity in personality may not matter as much as we instinctively think, certain personality traits seem to matter. In particular, neuroticism (the tendency to experience negative emotions) has been shown to predict lower relationship quality.
Although this may not be true later in life. Most of this research was done with younger couples, and in a trial with older and longer marriages there was no link between neuroticism and relationship satisfaction.
Some research has found that being open to experiences, being pleasant, and being mindful are very good predictors for relationship quality . However, these findings are generally not as strong as those with neuroticism. When asking people which traits they value most in a partner, the answer is loyalty and honesty.