Even if MC doesn't want to romance or bang Sage or both, its just human to help a friend in need. At that point sage let mc sleep at her place when he was in emotional drama with Josy and Maya. She returned him his guitar, and was geniunly friendly and nice with him (To my surprise I might add, I thought sage will be a big bitch, but DPC with his writing and character development broke all of my assumptions).
Jill should have joind MC and help to take care of sick sage.
Sage right now is in the top of my list of LIs. She is nice, Romatic yet Horny and is motherly in a sense, A dik and A chick MC will find her attrective since she is happy with Vanilla and expriments.