Most diets have rules. Some of those rules are convenient and simple and relatively easy to follow, and some are nearly impossible. Some fit great with certain personality types and taste preferences but not others. It's fine. That's one of the reasons there are so many. That, and there's a demand and people can make money selling diets, but that's another issue for another blog post.
Here's how to know if the diet you're on is not right for you: you're miserable. It's hard to follow. You are hungry and don't have enough energy. It's hard to realistically follow the rules. Any of these mean it's probably not the best thing for you (or possibly anyone).
Eating healthfully and maintaining an appropriate body weight doesn't mean you have to suffer. It is possible to enjoy food and life while taking care of your health and weight. In fact, it's really the only way to do it over the long term. No one wants to stick with a diet or lifestyle that sucks!
Do you have a "my diet made me miserable" story you'd like to share? Something that worked really well for you? Let me know in the comments. Or, if you have questions about a specific diet, let me know what it is and I'll see what I can come up with for you!