Even though she had meant it kindly, suggesting Rufus might be gay was the worst thing that Beth could have done. Or possibly the best thing, depending upon your point of view.
It instantly made Rufus's cold blood boil... perfect condition, when combined with Viagra. His ruthless soldier was standing to attention, ready for violent action.
He then inflicted upon the poor, kind Beth, a bout of brutal, self-gratifying sex, leaving her bruised and bloodied.
Maybe Rufus should have killed Beth then too, because she might talk. But he really liked her. Killing decision deferred.
His mistake this time.