Why does Curley get suspicious every time Slim is not with the other men in Of Mice and Men?

Curley, a antagonist in the novel Of Mice and
Men, is a very suspicious man. He knows that his wife is an attractive woman
and that a ranch full of men is not a "safe" place for a woman to
roam.

That being said, Curley knows how all of the ranch
hands look up to Slim. Slim is indirectly described as being the one on the farm with
which all others compare themselves to. Curley is surely jealous of the respect the
ranchers have for Slim, as well as, an almost certain jealously regarding Slim's
attractiveness as a superior male.

Curley always assumes
that if Slim is not with the other ranchers that he is with his wife. Knowing that
Curley maintains great control over his wife, he would surely have a problem with her
"stepping out" on him with a hired hand.