Thanks for the reading reference. We're always looking for something new to read!
I'm glad things are going so well for you on the new job. I think the reason you are calmer is a combination of all three. You are wiser, more mature, more accepting of yourself and others.
It is good that you recognize you're own need to decompress when you get home. I don't think H would take it badly if you just told him straight out, "H, I don't want you to think I don't want to be around you or that I'm upset with you when I get home from work. I just need a few minutes to unwind and debrief for the day, so I'm going to go hang out on the deck by myself for a few minutes." Or something to to that effect. If anything, he might even appreciate it. Use Martian language. He'll understand.