They're not obligated to invite you anyway, you horny weirdo.

A common sentiment I'm sure, but you certainly don't want to get caught up in that fiasco.

It's super weird that you're actively erasing their obvious bisexuality with your "boo hoo women I thought were straight aren't ******* me :(" thing

Maybe you can blackmail them into a threesome. I can't imagine anything going wrong with that plan.

First of all, if they are in a sexual relationship with each other, they are not heterosexual. You do realize that heterosexual means a person is only interested in the opposite sex.... right? If a woman is attracted to women AND men, she's bisexual. Secondly, it's weird and creepy that on some level you feel entitled to be involved in a thresome with them just because they ARE bisexual. Thirdly, just because they are bisexual does NOT mean they are into threesomes at all. And fourthly, unless they specifucally stated that they are cheating on their spouses, they may not be. They could be practicing ethical non-monogomy. That means they may be in this relationship with the full knowledge and permission of their spouses. And lastly, their sex lives are in no way an FML for you, as it's none of your business, doesn't affect you in any way, and has nothing to do with you.

Since they're not interested in some creepy incel bastard joining them may I suggest you go **** yourself? Literally and figuratively. I mean they're bad for cheating on their partners, but you take the cake here, pal. Jeez...