Institutionalized Infidelity

As I explore more of the erotica genre, I am surprised to see how often infidelity plays a role in the story. Typically, I find this in the vanilla stories I read. The story will be lush and erotic, two people coming together in passion exploring each other sexually. Maybe they're strangers, maybe it's a little kinky and then … BAM … the mention of the wife or significant other. Immediately, I feel cheated and wish I hadn't read the story.

I don't understand why infidelity has become...