When months, or even years, have passed and the memory of a past romantic rejection still stings, it may be because you believe the breakup revealed something about who you are as a person.

Remember how devastated Meg Ryan’s character was in the romantic comedy “When Harry Met Sally” when she learned that her ex-boyfriend was engaged? It’s not that she wanted him back, she insisted through sobs. But the news was still devastating. She listed all the reasons he must not have wanted to marry her:

“I’m difficult.”

“I’m too structured.”

“I’m completely closed off.”

The fictional Sally Albright viewed the failed relationship as a reflection of herself.

A recent research study by Stanford University psychology doctoral student Lauren Howe and her professor Carol Dweck explored why some people are haunted by past rejections and others move on more easily. The answer may lie in how people see themselves.

Howe and Dweck found that people who believe their personality traits are fixed have a harder time getting over rejection.

Beginning in childhood, people have assigned us adjectives. Some kids are shy. Others are class clowns. Kids are lazy or natural leaders. And the labels stick. But people are not static. Experiences, relationships and maturity can fundamentally change a person’s personality.

Yet even as a person evolves, it doesn’t always change how they define themselves. They put themselves in these personality boxes and may then blame those fixed traits when things in their life go wrong.

This is particularly potent at the end of a relationship, Howe says. A person, after getting to know you, has decided they no longer wish to be in a relationship with you. If you believe your personality is fixed, you are more likely to link that rejection to your sense of self — that something is wrong with you.

[One woman’s bold challenge to those with mental illness: Declare #imnotashamed]

Howe’s research found that people who agreed with this statement — “The kind of person you are is something very basic about you and it can’t be changed much” — were more likely to view past romantic rejections negatively and report that the rejection made them question their own self worth.

Additionally, those who believed the relationship ending was a statement about who they are as a person were more likely to want to suppress the memory and did not view it as a learning experience. When asked to write about their past relationships, the study participants who believed personality is fixed were more likely to say the breakup revealed that they were an individual who is, for example, too sensitive or too needy.

Holding on to past hurt also influenced how optimistic the participants were about future romantic prospects. They worried the personality flaws that ruined their last relationship would impact the next.

But personality is malleable. Even if a person was overly sensitive or needy in a past relationship, there are many outside factors that could have influenced those behaviors.

So it may be that one way to let go of the past is to first let go of the idea that how you were then is who you will always be.

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