Never had to fake, never been faked on either, as far as im aware. But im also the kind of Person who makes sure. I.e. i am able to stall my own orgasm, given that im probably going to be there faster than she would be, hence holding back a little. Of course once you get there anyway, and now considering she might fake it. I go for round 2.
Sex for me usually lasts at least 1 Hour, or several, depending on how "enduring" i am, which varies from day to day. Alas i could probably fake it given that i actually have to moan willingly, i.e. pushing myself to do so, else its just a little heavier breathing xD