Sex addicts have fears of abandonment and judgement. Their fears build unconscious expectations that their partners in relationships "make them feel" the way they do. This is called "the victim stance," and it runs rampant in our culture. We habitually blame another person or situation rather than taking responsibility for the realities we choose to create. I say "choose" because our realities and reactions are products of our personal experiences. What might upset one individual could mean nothing to another. A person's response to a certain situation or other person is determined by his or her individual experience.
For example, if every time your caregiver beat you, a red light turned on, you became conditioned to respond when you saw a red light. You may break out cold sweat, your breath may become shallow, or you may panic.
Or let's say that your mother was controlling, or yelled or withheld attention when she was upset with you. You will respond within your relationships the way you responded to her. You will react to certain behavior, tone of voice. or other nuance that taps into your original wounding or trauma. This is why the implementation of boundaries -- for both partners -- becomes crucial as relationships develop.