I quickly learned from my first sexual relationship that this wasn't true.
The guy I was with rarely wanted to have any sex, so I was entirely miserable for the 3 years we were together (yes, we lasted that long! First love and all). It led to other problems in our relationship.
This stereotype is a shame, as it made me feel unwanted (as females, we're taught to think that men always want sex, therefore if they don't then there's something unattractive about us). I'm also pretty sure he felt like less of a man for not keeping up with my sex drive and more often than not leaving me frustrated.
Lesson learned. Sex is extremely important in relationships, to both genders. Couples just need to find partners with matching sex drives.