Complex sentence: Because stonewalling is a physiological reaction the stonewalling can be thought of as a fight or flight response, psychological stonewalling is a defense mechanism in order for one to preserve one's self and emotions.
Split into simpler sentences: Because stonewalling is a physiological reaction the stonewalling can be thought of as a fight or flight response. Psychological stonewalling is a defense mechanism in order for one to preserve one's self and emotions.