It might be a time when you tell your partner the relationship needs to be upgraded. For most people confrontational situations require courage. You can build skills through training and practice. Training often requires seeking outside help from a person, a book, a video or a combination of these. For instance, if assertiveness is your challenge, consider taking an Assertiveness Training Class or reading one of the several excellent books available.
Practice requires patience, discipline and endurance.
All too often people quit things because the skill does not come easily, yet with persistence, the skill would have been acquired. And when difficult skill is mastered confidence and self-esteem go up. I believe most people struggle with fears in this category by dealing with situations that are challenging yet need to be mastered. These situations call for extra alertness. Being alert and aware is the focal skill needed in self-defense and soul defense.