Hi Slowly! I'm sorry you've been low lately, but you seems to have really pulled yourself up by the bootstraps! I have to say, some of NG's behaviors totally resonate with me, as they are very similar to S's. Having difficulty saying please and thank you (S. has a really hard time apologizing, as well), difficulty with acknowledging things (S. hardly ever acknowledges my e-mails if there's nothing to respond to, like an explicit question), general guilt causing withdrawal...
I think it's agonizingly hard to deal with (as do you, I gather), and I admire the way you have managed to look within rather than lash out at NG. One thing I do think you could do better is loving detachment, and as an actionable extension of that, I would agree that not always accompanying NG on his business trips may be a good idea. But rather than coming up with an excuse not to go, why not just let him know you'd like some space to yourself around the house? Would this wound him? or could you do it in a way that he would understand?
Could you clarify one thing? When NG said he had to run to a meeting, then you met for lunch anyway, how did that come about? Did you assume that his meeting meant no lunch, and it didn't mean that at all? Or did he arrange his schedule at the last minute to accommodsate his promise of lunch? And if you did indeed have lunch together as planned, why were you still upset (on into dinner)?