I remember talking to a friend of mine years ago who told me that she'd never had an orgasm with a man — but that she almost always faked it.
It really surprised me because she seemed otherwise like a take-charge kind of woman — confident, beautiful, and certainly not shy. I didn't understand why she'd feel the pressure! (She was an actress, though, so I guess that kind of makes sense.)
Most of us are not actresses, or not good ones anyway, and it doesn't make a lot of sense to me to pretend your significant other is doing something right if he's not. Isn't faking something you'd just have to keep doing? And then if you stopped, he'd wonder why whatever he was doing before no longer worked?