For a while I've thought to myself that Janet seemed half-in-love with Naomi, probably because she's beautiful and the first friend Janet has made in a long time.
We have no idea how much time these two women have spent together, although we do know that they definitely have spent time together, nor what they have said to each other, done with each other, nor how intimate they have become privately.
There is absolutely no way in the world that an over-sexed nymph like Naomi wouldn't have tried to get gorgeous and vulnerable Janet to respond to her sexually. (Naomi would probably think that involving herself in that way with Janet would be a good thing for Janet and bring her out of her shell.) The MC is 100% completely and utterly under Naomi's spell, lying because of her, breaking his word because of her, behaving dishonourably because of her, and I fully expect Naomi to try to work the same black magic on Janet in an attempt to make both Janet and the MC toys and playthings like Tasha.