I've had good and bad experiences with couples. Your generalising acting like they are basically all horrible is bullshit. And I know what a one penis policy is. I really don't see how it applies to the thing you are complaining about though, couples with straight men and bi women wanting specifically threesomes. Of course that pairing is going to be looking for a woman it's who they both like except for in cases that they have actually said not seeing lesbianism as valid is the reason it's ridiculous to assume it is. And that's what you are doing with your post.

Your post acts like 99% of couples who try to do this are horrible and says you just need them to stop. It's not just saying "I've had negative experiences" it's overly generalising people who are into that.