If you want a loving, long-lasting relationship, you need to be humble.

In a world filled with self-aggrandizing online dating profiles, it may seem counterintuitive to think of being humble as a relationship magnet. But "humility is a direct expression of someone who is truly confident and possesses high self-esteem," said Shaelyn Pham, a psychologist in Los Angeles and author of "The Joy of Me."

It may be that simple — and that hard. Simple because humility involves mainly one thing: sacrificing self-gratification to meet your partner's needs. And hard because that doesn't come naturally for many people.

"Cultivating humility can be tough, especially because the people who need it the most might not realize they're lacking in it," said Daryl Van Tongeren, assistant professor of psychology at Hope College in Holland, Mich.

Van Tongeren is co-author of a study published in "Couple and Family Psychology: Research and Practice." He and his colleagues examined how humility creates a self-fueling circle of trust and support, which in turn is powered by the reward of increased commitment. They also found that humility in a partner creates a capacity for greater forgiveness when he or she is rude or hurtful.

"When you're confident of who you are and who you're not, you're open to learning about what you do not know," Pham said. "So when issues arise in a relationship, those with humility are more willing to listen to understand [rather than] listen to be reactively combative."

Lisa Ryan, a counselor in Westport, Conn., agreed.

"In clients who are humble, there is not a major drive to be right," Ryan said. "They are more likely to accept a point of view other than their own as having validity; they have less of a need to lobby their spouse or partner to see it their way."

In turn, true humility also is linked to acknowledging and working on weaknesses, because the self-esteem heads off arrogance that's really just a cover for a low self-image.

"Humble partners are more likely to hold themselves accountable when things go wrong in a relationship," Ryan said. "They're also more likely to apologize readily and accept an apology with grace."

So does humility need to be predominant in all successful, long-lasting relationships?

"My guess is that a relationship needs much more than humility to be successful," Van Tongeren said. "But I do think humility can help. When people enter into a relationship, they have to overcome their selfish mode of operating, which has served them well in single life."

There is, though, the possibility of a "prisoner's dilemma" in relationships, he adds. "Imagine that people can either act selfishly or selflessly. If you both act selfishly, it's not great, but it's not the worst outcome, because at least your needs are being somewhat met."

Clearly, the best of all worlds is if both people act selflessly because that helps the relationship flourish. Each has the other's best interest in mind, Van Tongeren said.