Most men in anger management are to some degree, loners. They keep their negative information to themselves. Sharing with another man is alien, so when problems come up they keep the dialogue to themselves which gets wildly one-sided and leads them into destructive actions. In group they do talk amongst themselves to an extent, which for many is the first time this has happened. When they leave they often go back to their isolation.
In traditional societies men had tribal associations where issues were tabled. It was natural for the men to trust each other and see themselves both as competitors and as brothers. Modern gangs use the terminology of ‘brothers’ to enhance cohesion. The modern man needs some contemporary parallel to the tribal model. Finding another man they can respect and trust occurs in self help groups with sponsors. It also is available in men’s groups where it is safe for a man to let down his guard and be vulnerable with other men. He can admit to others he doesn’t know how to deal with his significant other and get productive feedback on how to approach the issue. This is a far cry than just listening to himself
In addition he can be challenged and challenge other men on their BS and stay proud of his own masculinity generating some self confidence. This draws him out of isolation and gives him supportive vibes with his own sex. It is generally better for a man to talk to another man about problems with his female mate than to a woman. A man can say things to another man which he will accept but would reject were it coming from a woman.