First of all, accept the fact that weight loss is not just determined by your eating and exercising habits. It is influenced by a lot of things. Every person has a distinct weight loss journey. So, you do not need to worry if the other person is shedding kilos faster as compared to you. You should focus on yourself and stay motivated to reach your goals.
If you crave for your favourite treat, then it is not bad to indulge in it sometimes. But do it in the healthiest way possible to stay on track.