Sometimes it's like with food. Let's say your favorite food is pizza. If you eat it every day, you will eventually get tired of it. So you take a break from pizza and how long till you get the taste for it back again varies with the person.
I can relate to that.
that happens to me almost every time I find a new food I like/love, similar to pron~
if one views a lot of porn within a short amount of time, it gets old and boring