Why cheat yourself out of an O by faking? For no good reason, lol.
I think many things that lead women to fake have been mentioned. But, there are others that lead women to fake to begin with:
--you can be as HD as you want to be and still have difficulty reaching O or take a long time reaching O or be unwilling to tell P that IC alone won't do it for you --to be hot and sexy --to not feel defective because P can't bring you to O --to be like a good sex P is "supposed" to be --to be the guy's fantasy for one night that then gets you plunged into a pattern of deceit (lies have a way of doing that) --sexual insecurity and performance anxiety --to get the O expectation over with so you can relax and enjoy the sex
The one thing I would say about the other comments here is that YES, there is pressure (unintentional or otherwise) from men for women to O, and to do so with too little foreplay during IC. BUT, (1) it is still up to the woman not to fake and (2) the woman may feel the pressure to fake because of social pictures of what good sex is "supposed to be like" no matter how understanding her lover. My point here is that it is far from being a simple problem of what H expects from his W in terms of Oing. Sure, that can be part of it. But, the social message women get that *sexy and desirable* women have strong vaginal Os at the drop of a hat from IC is a huge problem.
As for faking being better because the W is at least there physically, I'm really not sure that is better. Again, this is with the Faking Problem, not the occasional fake. Anyway, with the Faking Problem, you make your P an unwitting participant in producing and maintaining the sexual inauthenticity that is at the core of the problem. You allow someone to give of themselves in a deeply loving, vulnerable way and aren't emotionally present for it, which is an incredibly hurtful thing I think.
With emotional neglect and physical neglect, either can be more painful than the other in a particular case...
