Responses

Actually the Duke was just trying to ease the pain caused by the aphrodisiac. And the royal physicians said the only way to do that is by releasing the pent up desire-- which means sex. The Duke even mindful enough for Jace's consent this time to suggest Phil instead to do the deed. But Jace don't want anyone else but the Duke.
So yeah, you're just reading too much into it. Or maybe it was actually me.
Low key uncomfortable asf he just got raped and the first thing the Duke thinks is HMMM SEX?? Isn't he literally one of the causes of his trauma- maybe I'm just reading too much into it