What are the actions that lead to Lennie killing Curley's wife?

Curly's wife is incredibly lonely. Poor Lennie is the only one who will talk to her. So, she flirts with Lennie causing all kinds of conflicting emotions which Lennie can't comprehend. Lennie falls back to soft things which comfort him. He grabs her hair and doesn't stop petting. Curly's wife tries to get away. Lennie tries to keep her quiet and in the ensuing struggle he inadvertently breaks her neck.