Second, I really would have no way of knowing what his response would be if I didn't come home. I just feel as if he knows I will always be there, as if I am waiting for him to come home and I am not.
You're not doing it for him you're doing it for you. But the point is if you are sitting home and as you have said you feel a bit left behind when he is out and you're just there waiting. Then you should do something to change that.
You don't have to go out to bars etc. Go over to a friends house. Go see a movie. Go to a coffee shop and read a book. Or be in bed when he gets home. But if he feels like you're "waiting" that can produce feelings of pressure and guilt on him which is what he is trying to get away from (insert new jeep and drive off)
You will feel much better about all this when you start to take control of you and Your life. And forget about what H is doing
My goal is to some day be the person my dog thinks I am