The most common health issue that I see is fatigue. It takes a lot of energy to keep resentment in the heart and to keep fueling that resentment by replaying in the mind what happened. Forgiving can reduce the resentment, reduce the rumination, and increase energy.
It may help if your husband realizes that forgiveness and justice exist together. One can and should seek justice, and in my view, the quest for justice works well once a person already has forgiven. At the same time, once people forgive, they do not want to keep bringing up what happened. There is a tendency toward moving on. Thus, your husband, if he forgives, will not want to keep bringing up the injustice and, in all likelihood, he will want to leave it in the past.
We have to keep in mind that the forgiveness process is not the same as taking a journey in the car from point A to point B in the next 20 minutes. Forgiveness takes time, sometimes months. People need to take breaks to refresh. There is nothing wrong with taking your time and sometimes stopping. For how long do you stop? If you stop, say, for months at a time, then you might benefit from asking yourself if there is something getting in your way of forgiving. Are you afraid of forgiving? Are you simply distracted by life’s tasks? If so, then you might consider setting aside a certain amount of time each day or every other day to do the work of forgiving. Try to ascertain the reason for the stopping: the need for temporary refreshment, fear, discipline?
Research has shown that the initial decision to forgive is the hardest because it includes change and change can be a challenge. By change I mean this: The forgiver now has to start a journey, one that may not be familiar for the one who just made the decision to forgive. Those who decide to forgive know that they are committing to some hard psychological work. The decision, while difficult, involves courage.
The expression “no pain….no gain” does not imply that one must be in constant pain to grow as a person. In weightlifting, for example, the pain is temporary for more long-term growth of muscles and strength. I think it is similar for a person’s psychology. The pain from unjust treatment is our forgiveness-gym as we develop our forgiveness muscles. The point, as it is in weightlifting, is to stop the pain so that one can grow. So, we do grow as we go though the pain. We also grow in character as we forgive. In other words, pain, working through pain, and finding relief from the pain all work together to help a person grow in virtue and character.
Although you do not give specifics about the “problems” created either within the person or relationally, it does seem, based on your observations and concerns, that something indeed is bothering the person. If it were me, I would gently—-gently—-approach the person with your observations. As an example, you might consider saying something like this: “I am concerned about you as a person. May I give you some feedback in the spirit of helping you? You keep saying that you are doing fine and that your anger is not getting in the way (personally or relationally). Please do not misunderstand me. You are a friend and I like you very much. Because of that, here is what I see as getting in the way for you: (you can then list a few—not all—of the issues and see how he reacts).” If he begins to see some of these issues, then you have come a long way to helping him. Thank you for your courage to try. Perhaps you will succeed.
Yes, if the anger is short-lived and is a call to action to right a wrong. My worry, as spelled out in the book, Forgiveness Therapy, with Dr. Fitzgibbons, is anger that becomes prolonged (months or years) and intense. This can lead to a host of psychological compromises. We need to make the distinction between healthy and unhealthy anger.