Interesting! I am glad Lewis left out Romance and Sex, whatever his reasons; as you say, their absence removes constraints from his female characters. It also makes Narnia much more relatable for me, personally -- you see, I am asexual, so I find it extremely refreshing to experience a world where things that I don't care about are left implicit on the margins, as it were, and characters are allowed to be vital and normal without having to focus on sex all the time. :-)