Sweetie, of course you dont get it. That's because he is freakin nuts right now.
Trust me when I tell you that he is not ok. How can he be? He walked out on his family. You said it yourself, you have known him for 30 years. Is this something you could ever fathom that he would do?
They are very good at faking it because if they had to face what they've really done, it would bring them to their knees.
Nope, easier for them to pretend they are happy.
I know that when you are early into this you cannot believe that this was the person you were married to.
Remember that he knows there is something wrong. He just cannot figure it out. So, he tries to feel better. He thinks if he can get out of the marriage, then he'll feel better. When that doesnt work, he may try something else. But he will not realize until he looks inside that the problem is within him.
So, I know it is hard, but, try not to worry about whether he seems fine. He is not fine. He is broken.
What is important is that you will be fine.
And you will be.
Let him blow in the wind right now. His journey. Your job is to get out of the way and let him walk it.