Upside down, trust your therapist... if he/she says that a way to get them in the door is to ask them into a session "help you" try it. My therapist did this years ago in our first round of counseling and it worked well. It is because the your spouse mays see this a "your problem" and it sparks an interest in them to help you and maybe see their side. Of course it is not all your problem, it is on both sides. But the spouse not in therapy does not get that...until they sit there and maybe here something that is related to how they are feeling.
As far as therapist seeing you together, they all have their own deals about it, but they are treating the marriage at some point as a client, not just the individual. My T will see us both together, when my H got his own ( recommended as a good fit by my T) and we started seeing him as a couple, I agreed that he was still H's therapist first and foremost. I am guessing but if yours wants to see you together she/he has no problem with it.
Tell him the therapist would like to see you both together to help you... its the nothing wrong with him plan, you need help.
