Jimmy Porter is one of the most challenging antiheroes to come out of the twentieth-century theater. He is a frustrated man: though highly intelligent, the rigid English class structure prevents him from procuring a job worthy of his talents, as those are still reserved for those born into families with middle- or upper-class breeding. He is stuck selling sweets at the market and playing jazz part-time.
Jimmy also experiences great trauma from losing his father at a young age. He felt disconnected from the rest of his family and felt that no one else cared. Sitting by his father as he died left a major scar on Jimmy's psyche and left him without much in the way of direction.
Despite his justified resentment of the class system and his emotional wounds, Jimmy unleashes his anger on those who do not deserve it, especially people who are vulnerable, like his wife, Alison. From what is seen in the play, Alison has done extremely little to vex Jimmy: she is faithful to him, attracted to his sexual charisma and intelligence, and sticks by him despite his bad behavior, but Jimmy berates her for the sin of being from the upper class and for being unwilling to break ties with her snobby parents. He even claims that he wishes she would miscarry a child (not knowing she is pregnant) just so she could appropriately suffer and understand his own pain.
One problem with Jimmy is that he does nothing to change his life in any way, small or large. He is not politically active and does not try to engineer social change as an activist would, though his anger and energy would make him suited for that (Helena says he should have been born during the French Revolution for this reason). He stews in his anger, only making himself all the more impotent in making a break.
Another problem is that he is so self-absorbed in his own suffering that he declines to notice others in their suffering, such as Alison in her isolation or Helena in her frustrated dreams of being an actress. He feels that he is the only one to have ever known pain and therefore that he is unable to truly connect with others. He assumes that Alison has had a cushy life and takes her stiff upper lip in the face of his abuse to mean that she must have no sense of feeling or zest for life at all. Ironically, Jimmy is becoming the snob he accuses his wife of being, in that he assumes she is less "alive" than he is.