Younger couples tend to have sex frequently compared to the older people. This may be because younger people are much more energetic and their libido is usually high.
Is sex a determinant for a happy and healthy relationship? Studies have shown that a couple that rarely have sex are in an unhappy relationship. I believe that a couple under 25 years can have sex 3 to 4 times in a week that is if the distance between them is not an issue.