The game says, "You have to be careful how you use Donnie in combat' -- well I imagine fucking so! but the MC seems to be oblivious to how his self-centered dickishness just keeps planting the seeds of festering resentment. Right after acquiring Jessica, he sends his haughtiest and most self-important groupie to relay orders for him to pack for himself and a slave. The MC has over a dozen groupies (not slaves, let's get that straight) and he can't spare one to assist and comfort Donnie?
I know he's not being a deliberate asshole, and he seems like the kind of guy who would regret and make amends if he were only made aware, but no one around him seems sensitive to his pain, they just kind of ignore or brush off with mild regret every dog-kicking moment they're guilty of. Donnie biting back looks not only inevitable, but deserved. The MC is being an unconscionable shit.
The game gives you opportunity to send Jessica to have sex with Donnie. Wrong choice. You don't want to feed his fixation, he needs to get over it. There are plenty of seductive girls there capable of getting him past it. Giving him Jessica as a plaything and sympathy fuck isn't going to make things better.