No one here can tell you "why" he is doing anything. And if you can't trust his answers, it doesn't matter what he tells you, either.
I've chased a man I didn't trust before... but it didn't make him more faithful.
I think you are right - there is much to work on. My husband and I got some relief from couples counseling. We've gone off and on for years.
Your honesty about your anger is so refreshing, and I think shows some pretty good insight on your part. I know *I've* hung onto anger sometimes... because it was easier to feel than the pain and sorrow that was beneath.
It sounds like your H is on the road a lot.
You could travel with him
He could give up his career
Those are ways to solve the immediate problem. At some point you will have to figure out how to live with the idea that you can never know what he is up to. It may be that you won't be able to continue in the relationship until the trust is regained... and rebuilding it takes far longer than breaking it ever did.
I wish you the best.