The subjective nature of love and happiness makes it difficult to examine them objectively. Outlining the purpose of human life as the search for happiness and the avoidance of suffering, Freud began the systematic study of the psychology of love. His most enduring contribution was the discovery of the link between adult and infantile love. Oedipal love gives us the feeling of certainty about what true love is. Mutuality and positive reciprocity are the secret of happy love. Love is a strong motivational drive in life, a force for psychosocial development and a central interest for humanity. It has a remarkable power for the enhancement of integration. Love is a simultaneous attempt to find something new and re-find something old. The author examines which psychological factors lead to a happy result and what factors lead to failure.