[M4F] Bringing the Bull Home

So one day out of nowhere, my girlfriend of three years told me she wants to see a really big cock. Said she might go out and find herself some. I almost chocked but figured she's pulling me so I didn't pay much attention to her.

Then another night she pressed on. We were sitting on a couch watching tv (I forget what exactly) and she asks me if I want her to be happy. "Of course I want you to be happy, baby." I reply. She smiles and tells me she has particular needs I'm not helping her with. The after a brief silence she tells me she's met someone she likes. Again I couldn't believe what she was saying. I got a bit more worried this time but still dismissed it as a joke.

Now we're sitting at the dinner table. She's dressed very provocatively. I haven't seen her beam like this in a while. "So, David, we're getting a guest soon." she starts.

"What? Who?"

"Remember I've told you how I've met someone I like?"

This is ridiculous. "Are you kidding me? Babe, I thought you weren't serious. What is this?"

She smiles even wider. "Oh, you'll see soon enough."

"Forget it. I don't know what's gotten into you but we're not doing this."

"It's too late. He's bound to come any minute now. And he's not someone who takes no for an answer."

Hello all, I'm looking to play the cuck boyfriend and also the bull, unless you wish to share playing the dominant male. In your first message, please describe how you see the power dynamics in this triangle turning out. Hear from you soon!