BENONI, SA: Sean Penn is on the verge of proposing to Charlize Theron. Sources say the actor is smitten with the South African screen siren, and wants to make her his wife. “Sean can’t get enough of Charlize Theron,” gushes a pal. “I wouldn’t be surprised if he pops the question soon. “She isn’t intimidated by him. Sean wants to be with someone who takes no nonsense from him or anyone else, and he feels like he’s finally found his equal. “Charlize brings him peace, and he’s making it a point to watch himself around Jackson.–SY