I'm wondering if you might have more luck with a different guy for that. It sounds like she's ready.
She seems happy to keep Roger to herself. And ongoing. Maybe she doesn't want to risk that by changing the dynamic.
Are you ready to tell her what you want? She's told you she loves his big cock. I think you need to reply that you love that, and that you want to watch it fuck her tight little pussy.
For sure, Mrs. Screwher is well aware of my desires to watch Roger have sex with her. As well that I'm excited that she's taking such a member.
What you said about keeping Roger for herself is a possibility. That is something I can ultimately accept. I'm patient. I can wait for another guy. I just want to see my wife getting laid. But with Roger I'd like some kind of inclusion. One particular scenario I've thought of is them having their sex at our house. With me home of course. He can spend the evening with us. Then when they're ready they can go up to our bedroom and close the door. They can fuck all night privately in our marital bed.