The Knight in Shining Armor Syndrome or KiSAS (also known as the White Knight Syndrome) is an affliction most commonly observed in men but occasionally by women. The name of the syndrome comes from the classic format of a fairy tale: A damsel in distress is saved by the knight in shining armor and they live happily ever after. Sufferers of the syndrome search out others who they see as needing to be rescued and prey on situations where they can insert themselves as the shoulder to cry on. These people are attracted to others who have low self-confidence, are in a tough life situation, or have other vulnerabilities.
These symptoms often lead to short relationships a la rebound or longer term codependency. The latter arises when a Knight in Shining Armor comes across the sufferer of a complementary syndrome: the Damsel in Distress Syndrome. The rescue impulse in the Knight perfectly fits with the victim impulse in the Damsel. Thus, they mutually enable each other.
The sufferers of both of these syndromes are people who don't define their relationship, they let their relationship define them. The disease is unfortunately self-reinforcing and occurring at a greater and greater incidence as society puts increased emphasis on conformity and a lack of independence.