I don't see anything wrong with taking a break and just maintaining instead of actively losing. I take scheduled breaks like that, just to allow myself a breather and to also practice for once I've reached my goal and need to maintain. If you're feeling unmotivated, I honestly think the best thing to do is to give yourself a break so you can come back later with renewed energy.
Also, I've found you lose slower the closer you get to your goal weight. DO NOT feel like a failure! You've lost 51 lbs so far. That is not failing at all. Losing slowly is not failing, that's just how your body is working right now. You've just got to be patient and keep in there, you'll get to your goal eventually.