Idk about future chapters so i can only speak for whats happening here.
And what do you mean seducing the MC using therapy? He did meet his patient outside of the therapy and he is talking about the issue of the MC. I wouldn't call that seducing using the therapy.
In no way was it implied that the MC SHOULD meet the doctor outside the therapy. So if he accepted the invitation, it had nothing to do with the "authority" of the doctor.
And the MC is an adult and he knows whats going on. He isn't just blindly following the doctor. (You did mention that he was a college student as if the age gap mattered)
I do think that theres good reasons as to why a doctor shouldn't be allowed to get private with patients. Because doctors could abuse the trust we put into them or use the private info they have to manipulate the patient for example. But I just don't feel like this is the case here.
The doctor knows the MC has issues with erections, BUT he isn't using that info in an ill way. And the MC isnt in a psychologically state where he is easy to lead neither. That's why i dont think what the doctor is doing is morally wrong.
Your opinion seems heavily biased on the age gap, which is irrevelent since they are both adults.
Saying it is creepy and overall how you talk because one is 10 years older than the other shows how closed minded you are this matter. So yea I guess theres no point continuing this talk since i'm talking about morals while you are biased by your an age gap.

Wasnt said some chapters ago when the doctor was at a bar with his friends that he stopped fooling around or did i misunderstand?