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A Swedish study has found the key to a healthy relationship, and wow, it may be simpler than we think.

According to the study, published in the peer-reviewed journal PLoS One, if household chores aren’t divided evenly its women who suffer the emotional strain. The equality problem goes beyond who does what chore, but women can actually feel they don’t have equal footing in the relationship.

Researchers studied questionnaires about education, home life, health, and work, filled out by 723 residents from 1981-2007.

Research found that at age 21, both men and women reported roughly the same level of psychological distress, such as anxiety, restlessness, and concentration problems. Yet by age 42, that shifted, with women’s level of distress rising while the men’s stayed the same, according to the findings.

The biggest contributor for women’s distress was the unequal distribution of domestic chores.

“The results of this study indicate that it is not only a matter of whether the responsibility for domestic work is equal or not, but also the relational context in which the responsibilities are divided within the couple relationship,” the authors wrote in the study.

“It is not the work per se,” said American psychologist Jill Weber in an interview with WebMD. “It’s the feeling that the woman is not getting support from her partner. Inequality often translates as a lack of emotional support.”

So if you want a long and healthy relationship make sure everybody is pulling their weight around the house.