rewrite here - and recall that Arielle is a newly wed with her husband David who's less endowed than Diego (no need to say this; Diego is also about 6 inches)
"after here
“As Diana continued her conversation with Arielle, Dwayne began thrusting the Mandingo dildo in and out of Diana at an even faster pace. Diana tried to stay focused on the conversation, but her body was starting to tense up with pleasure.

Sensing she was getting close, Dwayne pulled the dildo out and spat on Diana’s face. “You filthy slut! You like it rough and dirty, don’t you?” he said, his grin turning even more sinister.

Ignoring Dwayne’s cruelty, Diana prodded deeper into Arielle’s sex life. “Are you sure you’re satisfied with David?” she asked, her tone argumentative.

Arielle bristled at the question. “What are you talking about? David is amazing. We’re very happy together,” she replied defensively.

But Diana didn’t let up. “But what about Diego? You said he was the biggest you ever had. Are you sure you don’t regret being with David now that you know he’s… lacking in that department?” she continued, her voice laced with doubt.

Arielle’s face grew red with anger. “How dare you! That’s none of your business,” she shouted, her tone turning hostile.

Diana could sense her best friend’s anger, but she couldn’t stop herself. The darkness and twisted desires that Dwayne had unleashed in her were too strong.

As the tension between Arielle and Diana grew, Dwayne just grinned, enjoying the power he had over them both. He knew that Diana was trapped in his twisted game, unable to escape”

in the heat of emotions, write how Dwayne whispers to Diana’s ear to ask Arielle would consider getting a dildo, a large 8-inch black mandingo dildo. get Diana to try to persuade the angry Arielle with dialogues"