The Piano: Rape?

In the movie The Piano, two characters, Ada and Baines have a sexual relationship that is quite controversial because it could potentially be considered as rape. But the the real questions is whether or not it is actually rape, or if it is a consensual sexual relationship. 

To summarize, Ada, who has not spoken since she was six, for no apparent reason, is sent off, along with her daughter to marry a man she has never met before, Stewart. Ada has been playing the piano since she was a little girl, and she sees it as her way of expressing her voice. When she comes to her new home to marry her new husband, he leaves the piano on the beach because he does not have enough help to carry it and does not understand the importance of the piano. Once she is settled in, she goes to Baines, Stewart's right hand man and interpreter, to take her and her daughter, Flora, to the piano on the beach. Afterwards, Baines makes an arrangement with Stewart that he would like the piano in return for 80 acres of his land, and that Baines would like lessons on how to play. This is just a ploy so that he can get closer to Ada and use her for her body. Once Ada begins to go over for lessons, Baines tries to make physical advances on her, and she is very upset by these advances. Baines then makes a proposal for her, that at each visit that she comes over and he is allowed to do things to her, then she gets one key back on her piano. She bargains back that she would do it for the black keys, which is far less than grand total. At one of their first lessons, he tells her to lift her skirt so he can see her legs, and he touches her leg through a hole in her stockings. This exchange increases every time that she goes over to his place: two keys for him to touch her arms, 5 keys to lay down with him with clothes on and 10 keys to lay down without clothes on. 

At first, it seems like this exchange could be taken as rape because it does not seem like Ada really wants to go through with it. She is reluctant, but eventually agrees. This is why I do not think that their sexual relationship is rape. She negotiates the terms of the sexual nature, and if she did not want to go through with it, she could walk out at any point. He is not forcing her into anything. Instead, their arrangement is more like prostitution. She is "getting paid" for her sexual favors. Prostitutes are not seen as getting raped, but rather offering their bodies in return for something they want. 

What is attempted rape though is when Ada is leaving the house to see Baines, and her husband tries to make her love him, and he drags her down and tries to force himself sexually on her. She desperately tries to escape, and she does not wish to have that sort of relationship with him. I think this is an important contrast to show the difference between her husband's attempted rape and her sexual relationship with Baines. One is completely not consensual, and the other is reluctant (at least at first, later on she goes willingly) but she does indeed agree on their sexual relationship. This is why I do not see the relationship of Baines and Ada as rape, but rather as a form of prostitution.