There is a lot of space between "Blowjob in a movie theater" and "Threesome with my mom", and in this kind of story—Patreon restrictions or not—there's no believable bridge to connect them together.
But a mother-daughter threesome is fair game?
I won't try to understand the extreme end of that spectrum, but I think Stephen having a biological child with Jade would be considered a much bigger sin than frat guys hooking up with a whore (I love you Rio, but I'm just being honest) or two lesbians eating each other out.
In any case, DPC does try and write.... mmmm, somewhat believable enough reasons for most girls to remain untouched, at least for some period of time. Missing husband, gay boyfriend, loveless marriage, sheltered princess, lesbian, too busy designing tattoos and being a shitty surfer I guess, Josy is sort of ambiguous outside of dating a girl, etc.