Peanut Gallery: Co-dependence is a natural consequence of our "infinite capacity for self-deception." We cannot look at ourselves squarely in the face of God's truth, so we we glance at others sideways as well. It truly is a societal disease.
Rebecca Hamilton has nailed it with her definition: "Co-dependence is... the fine art of making excuses for and buying into the lies of miscreants in such a way that you help them continue misbehaving. Meanwhile, you sacrifice yourself for them and their lies."
Why do we continue to enable other people's bad behavior? Ask yourself - "For whom am I continually making excuses and why?" If we are honest, it's not about them, it's about us... lying to ourselves.
Nothing will ever change until we face up to our own complicity in perpetuating bad behavior. The definition of insanity - "Doing the same thing over and over again and expecting different results."