For most people, it isn't necessarily not having a relationship that is the source of sadness, but a low level of confidence or lack of fulfilling emotion such as love. However I do sympathise, it is easy to fall into a negative complex, where you actually find comfort in negative emotions, and to some extent, when somebody proves your negative assumptions wrong, you can feel worse when you are meant to feel better (e.g. There are plenty of other people that are also single). Changing this attitude is gradual, but essential - talk to others about it to become more positive in yourself, it won't happen overnight. You ask for comfort but its difficult to provide that on a forum in any case, especially since we know little of your circumstances.