Yes, you are correct that in the end it is her choice. Still, it is possible that words might impact her choice. If she thinks that I won't mind because I don't care much about her, she might be more likely to give in to temptation. If I make it clear that I do mind very much, it might strengthen her resolve. And speaking merely theoretically, it is possible the use of phrases such as going to the firearms store, cutting off pieces of a man's anatomy in thin slices and then feeding them to his affair partner, or poison tipped bamboo spikes, might cause a woman to be more inclined to resist the urge. Not that anyone would act on such primitive urges. But as compared to "when I think of you cheating, I think of locking myself in a dark room and crying all day", I think more colorful imagery might help convey the depths of one's feelings.

When you can see it coming, duck!