If your marriage hasn't produced any children, I think it would be wise for the two of you to go your own way. You say he is "introverted" and has kept his feelings to himself in regards to his unhappiness with your marriage. What you fail to realize is that men take the approach to any problem as something that THEY need to solve. He has probably felt all along that your lack of interest in the physical side of your union was something HE was failing to provide for you in some way.
At the same time, if you are "ALWAYS" tired, perhaps it's time for you to consult a different physician since whomever you are seeing obviously has no answers for you.