Your wife is hot! You should totally let her play alone! My wife has always played alone. She's done a few threesomes and a couple of gang bangs - in addition to the many fuck buddies she's had!
My wife lost a bull with a "perfect dick" because I wanted to be there. He wasn't into being watched and she felt like she had to "perform" for me and just couldn't relax.
He only fucked her on two occasions and stood her up several times....