Chapters 9 and 10 see Catherine Earnshaw confess her love for Heathcliff but ultimately agree to marry Edgar Linton for the betterment of her social status. Heathcliff is also transformed after three years, and it is obvious that both he and Catherine are still very much in love. Whether Catherine's behaviour in these chapters can be viewed as anything but disgusting is highly subjective, as 'disgust' is perhaps too harsh. In my opinion the better fitted word would be disappointed, however Catherine's demanding behaviour towards Nelly is that of disrespectful and this in turn can be interpreted as a disgusting behaviour.
In chapter 9 Catherine tells Nelly that she has "accepted" Edgar Linton as her future husband. Nelly is quite interrogative at the revelation and questions Catherine on her choice, only to get back dismissive and pompous answers. Catherine's behaviour here is quite appalling, she uses imperatives: "be quick, and tell me I am wrong", and has an overly assertive tone: "you're silly, Nelly". It is possible to feel disgust at her demanding nature, especially because there is now a somewhat narcissistic streak in Catherine, and her tone in speaking to Nelly seems unacceptable. The use of the word "shall" when she says "I shall oblige you to listen" tells us that she is a spoilt girl who is used to getting what she wants. Her orderly and conceited manner of speech is also quite off putting. It can be argued that perhaps Nelly is trying to get Catherine to change her mind about marrying Edgar as she knows that Catherine and Heathcliff are exceptionally close, so Catherine's reluctant answer to why she wants to marry Edgar may provoke or irritate readers.
However, whilst it is easy to dislike Catherine's choice of marital partner, it is also easy to forget that Nelly is