If there are a lot of marriages without love in The Mayor of Casterbridge, there's also a lot of love without marriage. Lucetta falls in love with Henchard, then their marriage is postponed and then canceled altogether. Elizabeth-Jane crushes on Farfrae from afar for most of the novel. Henchard's loathing for his stepdaughter gradually morphs into a kind of hopeless, protective, and jealous love. She might be the only person Henchard ever really learns to love.
When Elizabeth-Jane first falls in love with Farfrae, it is in part because "he seemed to feel exactly as she felt about life" (8.33). In a sense, therefore, her love for him is really a narcissistic love of herself.
Elizabeth-Jane's affection for Farfrae is so pure that she is not willing to cause either him or Lucetta pain by acknowledging her jealousy and disappointment.