Where self-esteem is composed of positive emotional energy, or happiness, and is composed of the two types of self-esteem, called, "well-being" and "confidence," stress is the negative version of this.
Stress, then, is also composed of emotional or chemical energy, and yet is a negative form of it. Just like self-esteem, its opposite, stress can be in the form of either "hurt" or "loss" or both. The former feels like damage has been done to one's well-being, and one finds themselves even less meeting their needs than before. The latter, "loss," is a kind of threat in which one finds the possibility that an outside force may take away one's resources, and threaten one's money, friendships, relationships, job, social standing or any of a manner of things which leaves us feeling anxious, if stress gets past our personal boundary, to harm either our well-being or our confidence.
The first line of defense against stress is to "block it at the door" with our personal boundary, which is to "say NO" to it, to ignore or deflect it as Perseus did in defeating Medusa with his shield. However, if stress gets into us, its operations are still subject to the laws of thermodynamics, since it is an energy. When this happens, it will tend to deplete a certain amount of our self-esteem - the exact amount of positive energy that correlates to the exact amount of negative energy in the stress.
Specifically, hurt tends to cause us to lose the positive energy of self-esteem, called, "well-being," and the threat of loss tends to cause us to lose the positive emotional energy of self-esteem, called, "confidence."
Since "energy can be neither created, nor destroyed," we can learn to use the Anger Map and Anxiety Map to combat stress, and the pathological narcissism which often sabotages our friendships and romantic relationships. This comprises the major task of step five of human courtship, in the emotional attraction skill set that we call, "Finding Stress in Each Other." If we learn to beat stress as a couple, we are more immune to the forces that tear down friendship and love.