Pretty much the mindset of close minded and unempathetic people have for anything that isn't what they do/what they like/what they know and are comfortable with.

You don't understand it, it doesn't work for you, so of course it must be abhorrent/wrong/clearly abnormal. The people who engage with it/enjoy it/seem to understand it must be wrong, ill, broken or somehow incorrect; it can't be that your the one with the problem. "Someone else is the problem I am fine" is much easier to accept then "I am made uncomfortable by something I don't understand and that says something about me I don't like." after all.

Are open relationships for everyone? No, of course not. Not everyone's brain is wired that way. Mine isn't, but that doesn't mean I can't empathize and understand people who do. I'm about as generic and common as you can get (Straight white dude who likes women with curves) but that doesn't mean I think anyone who isn't like me is weird, or wrong. I certainly don't go around thinking the women in the world should all try and meet my standards (though that -is- what a lot of guys like me think).

There is no difference here. But hey, it's certainly an unpopular opinion, so it fits the sub. Its just also an opinion that self-labels you as I said, unempathetic and unwilling to admit the problem is on your end.