Tales of MU is an erotic fantasy. As such, it uses magic to remove any inconvenient parts of reality that might get in the way of the hotness. This includes cold feet: Amaranth's "nymph sense" seems to be completely reliable, so any scene she arranges is going to be hot, even if it is also awkward.
It's also trying to be didactic. There's no other reason for the multi-episode lectures about sexual ethics. But didactry and eroticism don't work well together, and they often work against one another.
It is difficult to understand why Ian would be so concerned about hurting Mack when he knows as well as anyone that any injuries he inflicts can be healed with a potion or two. This seems to include emotional damage; after Steff is raped, she spends a few days moping and getting counseling and "potions," and the only other effect we see of this is that she doesn't want to have sex in pools anymore. I may be missing something; I skipped most everything that wasn't in the main plot. But if rape is to be a plot point, I'd rather it be demonstrated as such in the main plot.
Didactic stories work best when they demonstrate their messages rather than merely explaining them. Tales of MU seems to attempt this; various characters embody various approaches to BDSM, so we might see them act out those approaches and live with the consequences. But it hasn't happened yet, and if it ever does, we'll already know the outcome, because of all the lectures.
Still, the prose is above par. The sex is adequately fappable if you're into BDSM.