Of course you do, most women find that they only orgasm one out of every two lovemaking sessions. It’s a rare (and lucky) woman who has an orgasm every time, which is why, for various reasons, including tiredness, stress and medication, you may find it hard to come to orgasm.
It’s also interesting to know that women can usually tell whether or not they’re going to work for them this time and if there’s any point in carrying on. Men sometimes find this hard to understand as they don’t have the same intuitive feelings, but this is the main reason women fake orgasm. It can be frustrating and uncomfortable to carry on when it’s just not happening.