"Jill had made very clear the type of dude she 'd be interested in ".
in that case you will not be on the sage path at all, and you will not have this dilemma. MC only accept automatically to Help Sage, if you are on her path. if you are not, She ask you, and you can decide if you want to help or not. and if you still agree, but then the Girl who are you interested in dating, and she is intrested in you show up and ask you out for a date, you expect that the girl should understand that you dumping her for a friend.
Its seems its your own dilemma, and not the game fault.
this is a either a decision between 2 love interest, or a love interest and a pal. and a pal would understand that you goes for the pussy.

.
but if it's a decision between 2 love interest, Jill has every right to be upset, that you rather spend the time with another girl, regardless of that she is sick or not .