I agree, you need to initiate some communication here if he won't be the one to initiate.
Re (from Post #3
"Is it unreasonable to want to be informed when he makes plans with her, beforehand, not to find it out when I call him and hear her in the background?"
I would, like, ask him that question verbatim, point-blank. "Honey, it would help me a lot if you could inform me when you make plans with her, beforehand. Would you be willing to do that? I hate it when I find it out when I call you and hear her in the background."
That and express how you're feeling in general, and that you would like to be left at home alone a little less.