Stanley has a tendency to try and control everything, which leads him to hit his wife, Stella, who is expecting a baby, and rape his sister-in-law, Blanche. The reason Stanley's character wants to be powerful is that he wants to be respected. Stanley knows that he is "common" and knows that Blanche believes that her sister is too good for him.
Stanley's desire to hold power over everyone makes him rape Blanche while Stella is in the hospital giving birth to their child. He rapes Blanche to show her that he can have whatever he wants. This is the major cause which drives Blanche over the edge, so that Stella and Stanley have her sent to the insane asylum. Blanche tells Stella that Stanley had raped her; but Stella wants to believe it is not true, even though in reality she knows that Stanley had raped Blanche. Although Stanley does not crumble himself, the people around him suffer greatly from his actions and desires.
Blanche tries to put the blame on Stella for everything that has gone wrong in her life. Blanche tries to live in the past when things were a lot easier for her at Belle Reve, and she does not want to face the forbidding future. She constantly lies about her age and what has brought her to New Orleans to spend time with her sister. All of these things have led to the destruction of Blanche, which results in her incarceration in the insane asylum.
A Streetcar Named Desire truly shows that trying to fulfill one's desires is not always the right thing to do. Stanley Kowalski and Blanche Dubois suffer greatly because they had tried to act out their desires with disastrous results. In fact in the movie, although not in the book, Stella takes her baby and runs away from him upstairs to her neighbor for refuge.