In their world, the statement that there is nothing better than sex simply isn't true. I don't have anything to equate it to in order to come up with an analogy, but it's just not that important to them. They do it often enough to satisfy their needs, but since it isn't any big deal to them, and since their needs are being met, they don't give it a lot of thought. So when they're confronted with a statement like, "We only ML twice last year", they can't believe it's true. They know that they were never left wanting, so it just couldn't have been that low. They must have ML at least once a month.
