Jade costs you J&M.
Cathy costs you Bella.
By the transitive property:
Bella costs you Jill.
Jill costs you Sage.
Sage costs you Quinn.
Quinn costs you everyone.
I think Jade costs you the leverage of Burke (because the video, if you decide to give it, also phone messages with her as evidence that you are in a "relationship" with her, her neighbors as witnesses of your night visit...)
Cathy's panties costs you the leverage over her and Bella + Jill.
if you decide not to pursue anything with both of them, but you have their secrets to keep - you are the man of power & control.
Bella costs you picture on rooster with her on the pool and all DIKs as witnesses of her night stay in the DIKs mansion, and maybe some conflict with her husband when/if he is coming back, and probably rumor of student/teacher relationship that might cost her job or even worse.
I think Jill & Sage are the main LI that must be pursued not both of them, just one of them... and the other must stay as best friend. My goal on that matter will be if it's possible ofc to make Rusty & Jill my good or best friends and work to get them back together and take Sage for me. In that scenario you will have B&R on your side and counselors as a puppets.
Josy&Maya friends and probably control over HOTs after Sage graduate and some of them become next president or vp...

Quinn on rehab or don't care.
Help Mona if there is a way to do it.
(This will be my approach to the main story... and ofc I'll play all other paths, because one DIK will rule 'em all!)