Having the same drinking habits as your partner could be the key to a successful relationship, according to research.

The research, published in the Journals of Gerontology Series B: Psychological Series found that older married couples who had the same drinking habits  – whether they drink or abstain from drinking – tend to be happier than couples where only one partner drinks.

They surveyed 4,864 married people with couples having been together for an average of 33 years to determine how drinking affected their relationships.

The couples were asked to answer questions about “whether they drank, how many days a week they drank and how many drinks they had on the days they drank.”

They were also asked about the quality of their marriages, “including whether they thought their spouses were too demanding or too critical, if their spouse was reliable when they needed help and if they found their spouse irritating.”

They found that the amount of alcohol people drank was less important than whether or not both partners shared the same habit of drinking or not drinking.

The researchers found that more than half of the couples they surveyed had two spouses who drank. Husbands were more likely to drink than wives, but for wives especially they were more likely to feel unhappy in their relationship if only one spouse drank.

Dr KIra Birditt from the University of Michigan told Reuters Health: “We’re not sure why this is happening,but it could be that couples that do more leisure time activities together have better marital quality.”