You know you're being manipulated. She could easily just let you watch. Your wife wants what she wants, though, so she's going to do what it takes to get what she wants.
Normally you'd have the power to resist, but it's been so long since she let you cum and you're not thinking straight. It was the same way the last time she made you suck her bull's cock. She denies you, she teases you like she did tonight, she gets you all worked up and then she makes you suck his dick just so you can watch him fuck her.
Some would say that she's cruel. You know better, though. You know that she's a good hotwife. She knows what turns you on, what gets you off. She knows that you're going to enjoy your cuckold handjob even more if she can whisper in your ear about what a good cocksucker you were.
No, you don't like giving head. You do, however, like being humiliated about the fact that you sucked cock for her. So of course you're going to take her up on her offer. You're going to walk into that bedroom and suck her bull's cock. You're going to get him hard for her. You're going to put his dick inside her, too, and you'll suck him clean when he slips out of her before you put him back in her again.
Then, when it's all over, when you've experienced the pure fucking bliss of watching another man cum in your wife, you'll get the handjob you want. You'll get the attention from her. You'll get an orgasm as she whispers in your ear about what a filthy fucking cuckold cocksucker you are.
She's a good hotwife and you're a good cuckold. Yours is a match made in heaven.
Now get in there and start sucking dick, cuckold. Make your wife happy by being a filthy fucking cocksucker. Get him hard. Put him inside her. Watch him satisfy her. Watch him make her cum and then enjoy your cuck handjob.