I've had a couple girlfriends that would take me not coming as a reflection on them, so from time to time when it wasn't going to happen I would fake it just so they didn't get upset.
And a long, long time ago as a teenager, I once faked an orgasm after the fact, as right as I was coming deep inside a girl she whispered, "whatever you do, don't come inside of me". I disguised the orgasm (how she didn't feel it, I don't know) and then pretended to pull out and roll over, fake finishing onto my stomach.
And that's how babies are born