Green’s Dictionary of Slang

(orig. US) to live or act alone; often with it.

1934		(con. 1901) E. Cunningham Triggernometry (1957) 331: Horn was notorious for ‘lone wolfing it’.
1944		R.F. Adams Western Words (1968) 93: Lone-wolfing Living alone, avoiding the companionship of others.
1955		R. Graziano Somebody Up There Likes Me (1956) 210: We don’t like the way you been lone-wolfing, Bob.
1961		N.Y. Times 26 Mar. VII 28: Is he lone-wolfing a top secret investigation in Italy? [HDAS].
2009		E.D. Hampel Gumshoe 164: You do what you want, lone-wolfing it, but as our dominant personality, I, Leo, can use all the help I can get,.
2012		D. Pendleton Lethal Diversion 123: You’ve been lone-wolfing it all night, and he seems to think you're the reason we’ve been running in circles. I need to know right now if you’ve been playing us.