If a person who supports bad habits and destructivebehaviour is an enabler, then a person who is unable to support these negative traits due to morals, a physical lack, or some other constraint is therefore an unabler. If you refuse to play into negative behaviours on someone's part then you are an unabler
Being a bloke I have to say this is actually what GIRLS do. They feel the need to play "hard to get" and therefore don't text back, though usually it'll be after a couple of texts so it doesn't look too obvious.
Me: I was texting Becca earlier
My Mate: Cool, how'd it go?
Me: Ok for about half an hour, then she turned on the old unable-to-text-back syndrome My Mate: Tut, of course...
Person 1: Has Sam texted you recently?
Person 2: Yea, her texting quality is so bad!
Person 1: Well, she's pretty stupid so that probably affects her unabletotextness.