When Elizabeth Bennet finally comes around to Mr. Darcy at the end of "Pride and Prejudice," she resolves to forget their former friction and, to the collective sigh of readers, accepts his proposal.

Now psychologists have confirmed what Jane Austen knew 200 years ago: In love, "a good memory is unpardonable."

New research shows that trust can distort our memories, causing us to view a romantic partner's past transgressions as less hurtful than they initially were. But for those with little trust in their partner, memories of a lover's lapse only fester over time, psychologists say.

"One of the ways that trust is so good for relationships is that it makes us partly delusional," said Eli J. Finkel, professor of psychology at Northwestern. In a few slightly different experiments, Finkel and his colleagues studied how college students reported and remembered a romantic partner's misbehavior. [6 Scientific Tips for a Successful Relationship]

In one study, a group of students who were in relationships checked in with the researchers every two weeks over the course of six months, each time, reporting whether their partner did anything to upset them.

Study leader Laura B. Luchies, of Redeemer University College in Ontario, told LiveScience that some of the crimes the students wrote down included: "She is hanging out with other guys and not understanding why I might be jealous at times;" "I made a major decision, and I didn't feel that he was as supportive as he should have been;" and "I visited him for Valentine's Day on a weekend that he was really, busy and he didn't didn't have any surprise romantic plans."

The students rated how strongly they felt the transgression was a betrayal, to what degree they forgave their partner, and to what degree their partner tried to make amends. (Each item was rated on a scale of 1 to 7.) During later sessions in the experiment, the participants were shown their own descriptions of the transgression and were asked, for instance, "Two weeks ago, to what degree did you agree with the statement, 'I experienced my partner's behavior as a betrayal?'"

The participants also filled out surveys to measure their trust, commitment, satisfaction and attachment in their relationships.

For students with a high level of trust in their boyfriend or girlfriend, memories of how they experienced these transgressions got rosier over time, but the opposite trend was observed in students who did not trust their partner.

The results held true even after the researchers controlled for sense of self-worth, willingness to forgive and attachment orientation. In other words, it was primarily trust — not the participants' low self-esteem, neediness or tendency to hold a grudge — that influenced their memories of something hurtful a partner said or did.

If you're worried that trusting your partner will bring you out of touch with reality, the researchers assure the kind of delusion that trust inspires is healthy for a relationship. Trust signals that it's OK to depend on a partner, and that you can be confident he or she will be responsive to your needs and look out for your best interests, the researchers say. In contrast, if you lack trust in a romantic partner, you might try to protect yourself from hurt and rejection by distancing yourself from this person and lowering your expectations of how he or she will treat you in the future.

Though the team only conducted the studies with college students, average age of 18, Finkel told LiveScience that they would expect to see the same results in older adults.

"We haven't tested our ideas in older samples, but my best guess is that our results would be similar there," he wrote in an email. "The tension between self-protection and relationship-promotion exists throughout the time-course of a close relationship. Given that trust varies among both older and younger people, it seems likely that high levels of trust should foster relationship-promoting memory distortions in a broad range of people."

Their work was detailed online this month in the Journal of Personality and Social Psychology.

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This story was originally written for LiveScience and was republished with permission here. Copyright 2013 LiveScience, a TechMediaNetwork company.