Enable (positive connotation) - Enabler (negative connotation). Why?

Solution 1:

Mentor or Motivator would work as alternative terms. (I like catalyst too)

Enabler picked up its negative connotation from psychologists. In relation to behavioral psychology it refers to someone who assists a person with self-destructive behavior - not just drug use, but addictions or negative behavior patterns of any kind. (Making excuses, assisting in covering it up, obtaining materials, etc). It's not technically a specifically negative term but at least in the US it's almost never used outside of the context of enabling addictions or other negative life patterns.