That happens, you know. It happens a lot. It happened to me after I lost 50 pounds in 2000.
There was a lot going on in my life in the years following the weight loss, and I lost focus. It is depressing, for sure, to gain back the weight after all that effort.
Let's consider the alternative. What if I had never lost that weight? Where would I be today? Probably over 300 lbs. Definitely discouraged and with horrible self-esteem. I would probably have marital problems due to the fact that I didn't care enough about us to take care of myself. Ashamed.
There is a lot said about yo-yo dieting, but I say this: at the very least, they are trying. It's not recommended, but it is a whole lot better than doing nothing. Those of us who are overweight will fight this fight all our lives. Every pound lost is a victory, and even everyday that we can maintain is another day that we did not gain weight. Victory.