Taking a break?

I posted this question to Karateforums.com.

I signed my children up for martial arts last October. They're been enjoying it, mostly, and I began in January.

However, they have been losing interest recently. At first, I just thought it was the usual thing that kids do: complain about having to practice and having to give up "free time" for lessons. I used to do that with piano when I was young! So I just did the old "of course we're going! You'll be fine once you're in class." And they usually were.

However, recently, I can see their loss of interest in the way they do class. They're just not trying very hard! They goof off whenever they can get away with it. They don't talk about TKD and work on forms at home like they used to. They tell me all the time that they want to "take a break" from TKD.

Perhaps this is more a parenting question than a martial arts question, but here's the martial arts question:

Can you "take a break" from TKD? Or, if you quit, will you inevitably quit for good? What are the benefits of taking a break? What are the hazards?

I'm not going to "take a break;" not yet at least. I plan to continue my study for a while.