While most Americans experience marriage or serious relationships during their lifetime, a growing number of adults are choosing to remain single. Although some studies suggest single individuals can be just as content as those in relationships, recent research indicates that couples may still have an advantage.

A German study surveyed over 77,000 adults aged 50 and older, analysing their Big Five personality traits -- extraversion, agreeableness, openness, conscientiousness, and neuroticism. The findings revealed that lifelong singles reported lower life satisfaction than those currently in relationships or who had been partnered in the past.

Singletons were also found to be less extraverted and open compared to their coupled counterparts. Women in this group reported higher life satisfaction scores than men, and older singles tended to be more content with their single status than middle-aged individuals. Researchers attributed this to older singles potentially moving past the societal pressures of marriage and family-building.

The study, published in Psychological Science, involved participants from 28 countries, with an average age of 68. Among them, six percent had never married, four percent had never cohabited, and three percent had never been in a long-term relationship. Participants rated their life satisfaction on a scale from 0 (completely dissatisfied) to 10 (completely satisfied).

Julia Stern, a senior researcher at the University of Bremen and the study’s lead author, emphasized the importance of addressing the needs of lifelong singles. "There are differences between people who stay single their entire lives and people who get partnered, and for me this means that we have to take extra care of these people."

She suggested that a lack of support systems and financial disadvantages might contribute to their lower satisfaction levels, especially in older age when health and financial challenges become more prominent.

Interestingly, the study noted that personality changes influenced by relationships could be temporary. For example, an extraverted individual might initially adopt their introverted partner’s traits before reverting to their natural tendencies.

The findings come as other studies suggest single people are at a higher risk of depression and that the trend of delaying or forgoing marriage may be contributing to declining fertility rates in the US.

Stern said: "When there are differences, they might be especially important in elderly people who face more health issues and financial issues. They need more help, and the help is usually the partner."