There should be a rule in JAV - never point the camera at any men alone once foreplay starts. It's just common sense. Some dumbass directors felt it was necessary to do a close up on the male actor's face in the midst of a sex scene...oh you want us to immerse ourselves in the story? We're here to jack off damn it get his stupid face out of my sight!
With that said, surprisingly, I find having a dude in the background having an inverse effect as it greatly enhances a raep scene. I don't have a cuckold fetish, but what it does for me is increase the distress and humiliation for the girl.
Here's Yuki Jin in RBD-656 for example. Pretty hot scene, although they're not grabbing her too tight. She certainly doesn't seem happy.
Then we throw a guy tied and gagged in the background with a gun pointed at his head!
Now it registers with us strongly that she's being forced to do this because his life is at stake. And we get a picture of her emotional state - being raeped in front of her bf. I completely indulge and embrace these dark fantasies as long as they're play acting!
I know I'm preaching to the choir as there's already an entire Raeped In Front Of Husband series, but housewives don't do it for me. And I've seen a few of those, doesn't the husband only show up at the very end and leave soon after? It feels like false advertising, I'd expect him to witness the whole thing, feel free to correct me if there are indeed episodes as such.