Amanda believes that Tom should be the provider for the family, much as a husband might do. Because Tom is the only son, Amanda believes he should feel obligated to provide for them. Tom and Laura's father left them long ago Amanda still believes that he'll return someday (he won't!), as she keeps his picture hanging on the wall. Tom does not feel he should be the provider and protector because he has his own aspirations and dreams. Too much pressure is put on him by Amanda and it finally gets to him. She nags him to no end about virtually everything he does, which would drive anyone crazy. Eventually, Tom realizes that if he wants to ever have a chance of being able to have his own life, he must leave both his sister and his mother. He feels particularly guilty about having to leave Laura.
Amanda nags her son Tom about the proper way to chew his food, she reprimands him for going to the movies too much. She returns a book he is reading to the Library because she thought it was inappropriate. She accuses him of being selfish.
But the most important aspect of Amanda's nagging has to do with Tom finding a suitable gentleman caller for his sister, Laura.
When Amanda tells her son that Laura has failed at the Business College, and that she is frightened for her daughter's future, which looks dismal. Tom says:
"What can I do about it? (Williams, p. 35)
"Overcome selfishness! Self, self, self is all that you ever think of!"
Tom does invite a gentleman caller for dinner, but on short notice, Amanda goes into a rant.
"Preparations! Why didn't you phone me at once, as soon as you asked him, the minute that he accepted? Then, dont' you see, I could have begun getting ready!" (Williams, pg. 42)
When the gentleman caller, Jim O'Connor, turns out to be engaged to be married, Amanda berates Tom for not knowing this important fact about his friend.
"You don't know things anywhere! You live in a dream; you manufacture illusions!"
"That's right, now that you've had us make such fools of ourselves." (Williams, pg. 95)
It is Amanda's constant nagging that finally pushes Tom out of the apartment for good. He abandons his mother and sister, never to see them again.