Certainly everyone could be pigs. But are they? Moral philosophy is heavily based on human intuitions. The fact that other people feel differently from oneself is (at least weak) evidence against one's own moral theories. There are many reasons to doubt moral prohibitions that are being slung around in public discourse about sexuality.

Declaration of morals is a social act. Isn't it a jolly coincidence how our promotion of certain morals just happens to make us look and feel better than other people? Isn't it convenient that morality gives us excuses to derogate our competitors? Perhaps even an excuse to go to war on them and take their land? While I believe that moral discourse is valuable and I engage in myself all the time, I do consider moral proposals to be suspect, because there is such a strong incentive for people to advocate morals for self-serving reasons without actually thinking them through in the context of moral theories that get fairly applied to everyone.

To a large degree, morality isn't about ethics, it's about status, signaling, tribalism, and policing others. There are many historical examples of over-reaching sexual morality such as religion, stigma against homosexuality, and suspicions about the sexuality of black men. Nowadays, there are other people who attempt moral prohibitions that are controversial, such as militant vegetarians, animal rights activists, environmentalists, and opponents of free speech on college campuses to name a few. Everyone political group wants to tell people what to do.

Since I'm a bit of a Hobbesian, I recognize that people will quickly violate any intersubjective forms of morality if they are left to their own nasty and brutish devices. Consequently, I would recognize that lots of moral prohibitions should be necessary. So, if I hear a moral prohibition articulated, shouldn't I find it credible? Not necessarily, because moral prohibitions have been appropriated by humans engaging in Hobbesian competition and weaponized. Well-founded moral prohibitions compete for our attention among a deluge of self-serving, incoherent, and hypocritical prohibitions.

Like White cards in Magic: The Gathering, moralists of every stripe think they stand on the side of goodness, law, and order, but that's hardly always the case.

In dating, there is also potential for bias proclamations about morality of how people of another gender should treat you. That's because people want to encourage behaviors that they personally find attractive, funnel the people they find attractive towards them, and avoid people they don't find attractive. If allowed to, they will stomp on the preferences of other people of their own gender, and on the preferences of the gender they are trying to date. Cross-gender claims about dating morality ("e.g. women shouldn't do this", "men shouldn't do that") are highly biased by the personal goals of the speaker, which doesn't always make them wrong, but does always make them suspect.

Now, what about moral prohibitions towards oneself? Those can still be self-serving, if you are using them to try to make yourself feel better or increase your status relative to others. See the story of the Fox and the Grapes. "I can't fulfill the desires of people I want to date? Well, I would've had to violate my lofty principles to do so anyway... what's more, the people who are doing better than me are pigs!"

Alternatively, even if your acceptance of restrictive moral principles is not self-serving, it still might show that one of your competitors has duped you and memetically neutered you for their own self-serving goals. Or perhaps you were influenced by someone else being the fox calling the grapes sour who wants you to be their partner in misery.

Moral prohibitions are important, and some of them are coherent and meaningful. Yet the above analysis gives us some priors about the sources of restrictive sexual and romantic morals which should cause us to think twice about moral proscriptions against personal development, including internalized ones.