The character who displays true love most clearly in The Crucible is Elizabeth Proctor. Her marriage to John Proctor has its share of problems; he was unfaithful to her, an error which precipitated many of the play's events, and she, through her own admission was a "cold wife" who believed herself to be unworthy of true love. In act two, before Elizabeth is arrested, both characters are seen to be attempting to repair the marriage but both struggle because she has not fully forgiven his infidelity and he has not fully earned back her trust.
Still, there is ample evidence in the text that Elizabeth loves her husband.
Elizabeth: My husband is a good and righteous man. He is never drunk as some are, nor wastin' his time at the shovelboard, but always at his work.
Here Elizabeth admits the truth about her husband (even with the knowledge of his many flaws). John is truly a "good and righteous man." She then gives a concrete example of exactly why with a reference to something every Puritan can understand: hard work.
In the final scene, Elizabeth is asked to persuade John to give a false confession. She agrees to speak with him, but does not promise to persuade him to confess, showing that her focus is on what he needs. Despite her desire to have her husband alive, she also understands John's desire for forgiveness and salvation, as well as his need to retain his good name. Elizabeth shows true love here by putting his desires before her own, by forgiving him and helping him to forgive himself and by convincing John that he is a good man regardless of his decision. It is her presence and strength that allow him to make the decision to die an innocent man rather than give a false confession.