This is definitely the most comprehensive version of an erotic supplement to 5e I've ever come across. The fleshing out of subclasses, backgrounds, and feats are welcome additions and each are implemented creatively.
I'll be using this to run a one-on-one campaign soon and am interested to see how it works during play, as while reading I'm feeling a bit of friction in regards to is how the Allure score is implemented. Having Temptation be the only skill tied to it and then using Composure to resist most sexual actions leaves it feeling somewhat vestigial. In that regard it might be better suited to being reworked as an alternate AC because you can only actively use it while trying to Arouse.
This in turn tugs at the implementation of Combat Sex. The only martial way to engage with the Arousal mechanic is by rolling Sex checks, which really flattens an otherwise detailed and rich system you've created here. There's really no character or skill expression outside of spells or class abilities and if you don't scale DEX your options for engaging with Combat Sex rely entirely on those or including kink/fetish bonuses.
I know this is all an entirely optional portion of your supplement so it might be better to leave it relatively shallow, but I think it might all work more smoothly if players were given a wide range of general actions to be taken as with regular combat. Having the choices of ranged/melee/grappling/hide/etc needs an analog to make solving an encounter erotically more satisfying-- otherwise the gameplay loop feels a little "mash A to achieve climax". Though this is all predicated on the notion that Climax could lead to a satisfaction or exhaustion state like unconscious that would end a battle, whereas currently the Stunned state implies you are just aiming to give your party the opening to deal fatal damage.
In any case! I hope this didn't come across as harsh. I've been looking for good erotic supplementation to 5e for years as a long time erp fan and DM. This was very sex/kink/queer positive, which is always refreshing to see and well research and written. Your art and layout are top notch and the sheer amount of content is astounding. I'll definitely be giving a rating once I've actually run the dang thing and am excited to see where it leads. You've done an amazing job and I'll certainly be following for any further projects of yours.