[The Mouth of Sauron]

As far as I can calculate, Celeborn and Galadriel were an "item" for at least 5,000 years, maybe longer.

Now Elves don't age - and Galadriel was by all accounts a very attractive female - and presumably Celeborn liked to sleep with her. So how come they and other Elven couples didn't have kids continuously throughout the ages ? Even at the comparatively modest breeding rate of one child every 10 years, why didn't Celeborn and Galadriel not have at least 500 children ?