The 19th century European concept of marriage as depicted in Wuthering Heights is largely based on social and economic advancement and not, as it is in modern America, a romantic notion. In other words, couples married to either maintain or advance social class or property (land), not because they necessarily loved each other.
Most of the characters in Wuthering Heights are members of the gentry (upper middle class), one step lower than the aristocratic class. On the heath, the Lintons are more well off than the Earnshaws. And the Earnshaws are more well off than the orphaned Heathcliff. So, Catherine Earnshaw marries Edgar Linton to become "the greatest woman in the neighborhood." She moves over from Wuthering Heights to Thrushcross Grange for socio-economic advancement. Even though she loves Heathcliff (the romantic concept of marriage), she marries for a better house and more land.
Heathcliff resents the concept of marriage to no end. Even though he turns himself into a member of the landed gentry, he is still forsaken by Catherine and the society. So, he plans revenge on the entire system: he abuses the concept of marriage to acquire both houses (Wuthering Heights and Thrushcross Grange). He arranges marriage between the younger Catherine and Linton as a cruel punishment to this second generation on the heath. His goal, I think, is to destroy the (romantic or economic) institution of marriage by abusing it to its extreme end.
In Wuthering Heights Marriage served more as a hindrance rather than a union between two people who love each other. Although Catherine was in love with Heathcliff and they considered each other one half of a whole they never got married and up miserable. Even though Catherine marries Edgar she still longs for Heathcliff and finds Edgars presence slightly bothersome. Although Edgar's sister believed she loved Heathcliff and he her when they got married he abused and mistreated her until she ran away. Then there is little Catherine who marries Linton out of the kindness of her hear but she just ends being mistreated, abused, and miserable. It's almost as if marriage signifies the end of any thing happy and or pure. The only time marriage signifies love is when Catherine and Hareton marry each other in this odd twist of events that were created out of hatred first then grew into fancy.
the novel wuthering heights takes place in the 1800s and the role of marriage is a lot different than what it is now. during that time men had a lot more power than women, therefore many a times women married in order to rise in the social status and power as we see in tthe case of Catherine and Linton's maarriage. though she loves Heathcliffe she does not marry him.Her marriage to Edgar is motivated by her desire to rise in the social status.