The whole motivational problem boils down to this question: Why am I doing this, anyway? I find that the food side of the weight loss equation is much harder than the exercise part. Sometimes it seems like it would be so much more satisfying to simply just enjoy yourself and not worry about losing any more weight. Some distant scale number in the future doesn't seem worth the decreased calorie consumption right now. You always have to weigh how you feel right now with how you think you'll feel in the future.
If you really don't feel like you need to lose any more weight, then you're done, and all you need is to maintain the weight loss. If you still feel like you have a bit more to go, it's up to you to decide how you want to do it. There's no rule that says you have to be on the difficult but faster lose-2-pounds-a-week path; you can choose to lose a pound or half a pound or even less a week. A diet is more than a calorie deficit; it's all about making healthy food choices. Every day is a blank slate when it comes to food, and you've only "ruined" your diet if you decide to give up altogether.