This is one of the most popular dreams of all, as most people dream about real-life or imaginary relationships. Everyone dreams about relationships because the man is a 'social animal' and he needs companionships and relations in order to achieve happiness, according to Aristotle's Ethics.
Depending on the type of relationship you see in your dream - a fulfilling, happy one or an unfulfilled one which brings anger or sorrow into your soul -, it bears a positive or negative significance. Such dreams most of the times reflect real-life situations and events - if your dreaming your relationship with family, friends, lover etc. brings you happiness, this means that you also have a fulfilled waking life and have reached emotional balance. But if you dream about a failed relationship or one which brings sorrow to you, this means that you also encounter problems in your real-life relations.
If in your dream you have a relationship with someone you know, compare the relationship in the dream with the one you have in the waking life with the same person. If they are different, the relationship in the dream may represent your hidden feelings towards that person. But if in your dream you have a relationship with a stranger, this may be a compensatory dream (fulfills your wishes in the waking life). A relationship with a stranger may represent your hidden, primitive desires or other sides of your personality you are not aware of yet. Please remember that other people seen in one's dream are usually parts of that man's personality.