It happened a while ago when my (now ex) wife was 26. For a while she had been moaning about being unattractive. This continued no matter how I tried to re-assure her. I asked if she had noticed other men eyeing her? She did not believe they found her attractive.
My wife let out a little “oh no” (not so loud) and looked at the ceiling, I leaned back in and kissed her again and during that kiss felt a jolt that indicated she felt Ken's hand touch her. I moved my mouth down and took her right nipple back into my mouth as I lay at her side giving Ken good access to her body. I felt the bed move slightly as he climbed onto the bed with us, his hands snaking up her body as she lay spread-eagle beneath him. Cupping her other breast, then moving up to join me as we both sucked on her nipples. I looked up, she was gasping slightly, but not looking at us or saying anything. I moved out a little and Ken cupped the now vacated breast and took a taste of it too. He gently caressed her body.
She arched here head and back, her eyes were open, and she was breathing heavily as I took her hand again. He took a look at her and pushed forward, my wife’s head jerked a bit and while I could not see, I knew from her reaction he had entered her. He kissed her neck. A few gentle strokes later he asked her softly "are you OK with this?" (Smooth!). He asked her after he had entered her. There was not much she could do or say now that his dick was deep inside her. She nodded almost imperceptibly, but certainly not saying no. Ken took that as a yes and started to fuck her with slow, strong measured strokes at first before building up the pace. I leaned in and kissed her hard again, feeling her respond and reacting to the good solid fucking Ken was now giving her.
I loved her reaction intensely as I squeezed her hand and partly embraced her. Feeling him fuck her as we kissed was awesome. I stepped back to enjoy the sight and to give Ken some space. He was clearly enjoying fucking my wife and she seemed to have accepted it and was enjoying it too. He continued to fuck her passionately until she climaxed and he came deep inside her.