Four sessions isn't very many guy. It is very probable that you are triggering each other and a good therapist will look into the behavior patterns that can stem from one's history. But that can take time and the idea is to help a couple understand each other better so they interact with their partner in ways that respect some of these challenges. Many members here do understand why her flirting triggers you, and it sounds like your wife doesn't get it. Yet, you also have done things that trigger her as well. And the whole point of this therapy is to find ways to change that problem you experience with each other.

Honestly, I met a woman that has a relationship therapist that her and her husband have met with for years, not so much to fix problems but to keep them on track with understanding each other's needs so their relationship stays healthy.