In the early stages of the book when we fist see Heathcliff and Isabella together, we do not suspect how their relationship will evolve. Arguably, though, things do not really change between how the pair feel about each other through the novel- true, things do waver a bit when Heathcliff returns but the feelings that develop there are both one-sided and short lived. Furthermore, to Heathcliff, Isabella seems to remain as little more than "Edgar's sister" even when they are husband and wife. The benefits in Heathcliff marrying Isabella are not merely financial, she also offers a means by which to wound Edgar and to interpose himself further into his thoughts and his marriage with Cathy. In this sense, Heathcliff's feelings towards Isabella have not gone much beyond his attitude at their first meeting- their marriage has more to do with Heathcliff and Edgar than it has with Isabella as an individual. To Heathcliff, she remains as nothing more than "Edgar's sister", a tool for him to cause destruction and for his own financial benefit. However, in Isabella being taken away from the Grange, Heathcliff has involuntarily made life better for Cathy and Edgar by remaining out of the picture himself so perhaps their marriage is also a tool for Bronte to change the atmosphere at the Heights
In the early stages of the book when we fist see Heathcliff and Isabella together, we do not suspect how their relationship will evolve. Arguably, though, things do not really change between how the pair feel about each other through the novel- true, things do waver a bit when Heathcliff returns but the feelings that develop there are both one-sided and short lived. Furthermore, to Heathcliff, Isabella seems to remain as little more than "Edgar's sister" even when they are husband and wife. The benefits in Heathcliff marrying Isabella are not merely financial, she also offers a means by which to wound Edgar and to interpose himself further into his thoughts and his marriage with Cathy. In this sense, Heathcliff's feelings towards Isabella have not gone much beyond his attitude at their first meeting- their marriage has more to do with Heathcliff and Edgar than it has with Isabella as an individual. To Heathcliff, she remains as nothing more than "Edgar's sister", a tool for him to cause destruction and for his own financial benefit. However, in Isabella being taken away from the Grange, Heathcliff has involuntarily made life better for Cathy and Edgar by remaining out of the picture himself so perhaps their marriage is also a tool for Bronte to change the atmosphere at the Heights