As we know, when a person does something which affects us negatively, our reaction will often depend on who that person is. For example:
You arranged to get a ride home with someone after a wedding. At the end of the wedding, you search for the person but cannot find him. Someone tells you, “He left already. Did he leave you stranded?” Your reaction will depend very much on who stranded you. If it was your father or brother, then your mind will immediately view the act as innocent and you will assume that there is probably a good reason for his behavior. If, on the other hand, the person who was supposed to drive you was someone that you know only casually, you might say to yourself, “He probably realized that he had no room for me. But how could he be so inconsiderate as to not even tell me?”
Of course, there could be any number of reasons why the person left without telling you. He may have been mistakenly told that you had already left, or that you wanted to stay late. Perhaps an emergency forced him to leave in a hurry. Or, he may have simply forgotten.
The Chofetz Chaim discusses a case where you have been told that someone said something negative about you or has done something against you (i.e. you have heard rechilus) and you have confirmed that the report is true. Nevertheless, says the Chofetz Chaim, you are obligated to judge him favorably if there is any possible way to interpret his statement or action in a positive light. If you do not judge him favorably, then you are guilty of accepting rechilus.
The Chofetz Chaim concludes by discussing the teshuvah (repentance) which is required of someone who has accepted rechilus as truth:
“He must work on himself to expel the matter from his heart so that he no longer believes it. If it is difficult for him to believe that the speaker fabricated the story, then he should tell himself that perhaps the speaker added some details, or omitted a detail or some words which had been said about him; or that the person uttered his words using nuances which would give his statement a positive interpretation.”
“The listener should take upon himself not to accept loshon hora or rechilus in the future from any Jew, and he should confess his sin (before Hashem). Through this, he will have corrected his sin, provided that he did not relate the information to others.”