My wife can't be NTR'd by my girlfriends. (Hyakuna Sarina, Misaki Kana, DASS-826)

I have a fetish. It's the desire to see my beloved wife, Kana, having sex with someone else—a so-called NTR (Netorare) desire. However, I absolutely cannot accept being NTR'd by a man. So, I asked my friend from university, a lesbian named Sarina, to hold my wife. Initially confused, Kana gradually became immersed in the pleasure, displaying an ecstasy I had never seen before. Seeing her like that, I felt intensely excited. —But after that, my wife started acting strangely. Kana began trying to see Sarina even when I wasn't watching, and eventually, she even disobeyed me. And then, the two of them embarked on an unusual relationship…