At least that's what I like to call it -- the "modesty paradox." I think it's actually a rather clever convention of McMurtry. We can see it in just about every male character with, perhaps, the singular exception of Gus McCrae. It is this: all the men in this novel have very cavalier attitudes towards casual sex, especially with prostitutes; but these men also are very shy and modest when it comes to actual intimacy, even to the point of being mortified with shame at seeing women's undergarments hung to dry on laundry lines. I think this tells us how free morals were when it came to sex, especially in how normal prostitution seemed, but also how behavior in the wild west was nonetheless colored by convention. As "wild" as the west was in the 19th Century, it was still heavily influenced by the mores of East Coast Victorian propriety. It makes for an almost incomprehensible paradox of life and morality in the American west.