Why was she begging for her ass to be slapped? [Cuckold’s perspective]

Hi everyone, I'm hoping to get some insights into a confusing experience my wife and I had. We're a 36-year-old South Asian couple living in the USA and have been in a hotwife lifestyle for about 6 years. Before she had her current boyfriend, our dynamic involved her playing solo with guys and sharing details with me later. Sometimes, she would even ask them to record clips for me.

This particular incident involved her first experience with a guy who had an exceptionally large penis. She sent me a photo of it in her hand, and it was bigger than her arm, thick like a soda can. My wife is a skinny woman, standing at 5'3", so you can imagine the contrast.

Later, she sent me a clip of their encounter in doggy style, where he was going in and out, and she was screaming for him to slap her ass. I've heard her say things like that before, but never with such intensity. She was begging him to slap her ass harder, and he did, but she was crying, begging, and asking for more while he was inside her.

I asked my wife about this, and she didn't know why she reacted that way either. She told me it was just a spontaneous reaction, but I feel there might be more to it. Does anyone have any ideas or similar experiences to share? I'm really curious to understand what might have triggered such a strong response in her. Thanks in advance for any insights!