It’s not that she let him have her ass. It’s that she didn’t even put up a fight. He said he was going to fuck her ass and she practically begged for it.
It’s different, isn’t it? You’re used to your wife denying you access to her ass. She’s never been willing to even consider it, and yet she happily got on her knees and let him mount her tight ass from behind. Now he’s buried balls deep in her bottom and you’re stroking your little dick.
“Only a real man gets to fuck my ass,” she says as you wank to the ass fucking happening in front of you. “And you’re not a real man, are you? Not with that little dick.”
What can you say? You know it’s true, cuckold. You know he’s always fucked her better than you. You know his dick is a lot bigger than yours. You know he brings your wife the kind of sexual pleasure that you’ve only dreamed of. That’s why he’s in her ass and you’re not.