Maybe you are mistaking your love for someone with your fear of being alone ?
Open relationships, and poly relationships even more, are difficult for many reasons I can't bother to detail here. There is of course a certain inequality in the access to sex that you are pointing out even though you are leaving out many other very important parameters in your example. But there is also a great inequality on how people are able to decouple intimacy/sex with a strong bond with someone, which can make someone suffer even if he or she did not think it would, leaving behind a mess of hurt feelings. But believe it or not, different people experience feelings for people differently and just calling them cold robots is just an easy way for you negate their existence, as some believed lesbians could not exist, they had to be frustrated heterosexual that had not met the right man.
Anyways your vision of the whole thing seems to be pretty much informed by your resentment (They are not even paying for dinner!) and it is not that hard to find someone to have sex with you as a man. Having some emotional intelligence, basic social skills, not having a definite vision of what gender roles are, and in general not being an asshole will help a lot, adding to that women are for cultural reasons less sensitive than men to attractiveness. What's funny with incels is that they complain they can't get laid but what they mean in general is that can't have sex with the most attractive women and make fun of less attractive women, in doing so revealing that what they are after is the social status of being validated by them and not to get to share a moment of pleasure and intimacy with someone else.