What makes Hindely-Frances relationship not good that much? And why we can consider Hareton-cathy relation as a good one?
In the novel 'Wuthering Heights' by Emily Bronte, the character named Hareton is one of the few who displays any true emotions or feelings and also one of the few who displays any common human decency. It is this potential for improvement and character growth that makes him a hopeful suitor. He may have benefitted in some small way from Heathcliffe's admiration for him, an admiration which borders on true affection at times, Even though he was initially a target for revenge and bitter retribution. Heathcliffe's first treatment of him was to degrade rather than support. Hareton appears to suffer real sorrow when Heathcliffe dies, and actually cries - seeming to display real affection. If this is so, it is a window of hope for Hareton as it means he is capable of love - and that's good news for Cathy.
In the Novel "Wuthering Heights" Hindley Earnshaw is very dependent on his wife. He has not ever felt loved or accepted in his home. He marries a girl whom he feels that he loves and when he inherits his father's estate returns home. It is after his wife's death that we see Hindley fall apart. He becomes abusive to the child that his wife had wanted to have with him.
Harenton and Cathy are almost like a younger version of Heathcliff and Catherine, Cathy's mother. They are still young and innocent enough that they do not have the level of baggage that Heathcliff had carried. Initially they did not have a good relationship. Cathy had been married to Linton who died. It was a marriage manipulated by Heathcliff.
Upon Heathcliff's death Harenton will inherit the estate. If he and Cathy marry they will be able to provide support for one another. Harenton is basically a good person. He is kind and does nice things for Cathy. After Cathy begins to recognize these actions, she too lets her guard down and they develop a relationship through friendship. These qualities will help to give them a good marriage. Cathy is also no longer worried about Hareton being unkempt or uneducated as she is teaching him and he is a willing learner. The barriers that were present for Heathcliff and Catherine are not there to interfere with their relationship.