You are not the exception to the rule. You will not cure them of cheating, because you're an awesome person. A cheater will always be a cheater. Especially, when they are cheating long into adult years.
Complementary (also known as supplementary or contrasting) colors are colors that sit opposite of each other on the Itten color circle. The combination of such colors creates a vivid and energizing effect, especially at maximum saturation.