Aside from the obvious "Parker is a full blown LI" so it would be hard for her to be an antagonist (or at least an irredeemable one), she's shady and more important : never present enough, so her development as a LI is pretty stunted for now (same for Riley who has no romantic/lustful feelings for MC whatsoever).
Perhaps we're given that peek of her shadiness to give us some doubt on her agenda....
But for me, Parker is no villain nor serious antagonist. At worst, she's an helicopter step-aunt, and she's wrong to be so secretive. She'll have to work some more if she want to be fully redeemed, though.
My biggest issue with the last update is that BS of MC having addictive cum and "pheromones" that attract and make him handsomier....er...handsomer...handso - fuck it, prettier to the ladies.
Meaning aside from Evelyn and Amber (whom we finally saw and damn, she's a knockout

) and perhaps a bit of Moonsong (cause now she's all ut addicted to MC's meta-schlong) ; no other girl is truly interested in MC, or at least not because they find him genuinely attractive ; and that's a bummer...