If you have some dinner by yourself, then it means you are trying to figure out which direction of life too choose. Perhaps you reached the point of your life where you need to make these kinds of decisions. The fact that you have the dinner on your own could also represent the lack of communications with those around you. Maybe you are the person who feels best on his own. If you are having dinner with other people and having a great time, then it means you are able to communicate with those around you. The dinner could also represent the important meeting that is waiting for you in the waking life.
Read more about dreaming of Dinner in other dream meanings interpretations.