Ultimately, good boundaries and clear, direct, non-aggressive communication skills go a long way to preventing and resolving conflict. Boundary work is often a big part of therapy. Those with appropriate boundaries are better able to communicate their wants and needs effectively, without guilt or reactivity, taking ownership of their own contribution without taking responsibility for another's.
Effective communication skills don't necessarily come naturally, but they can be learned. Like building muscle, developing good communication skills takes time and repetition. Skills can be taught, practiced, and learned. Going to therapy is to communication skills what exercise is to muscle development. You have to start somewhere! The therapy office is a safe place to begin.