The art and sound effects are very good. I liked especially the picture of the girl when the phone rang especially.
I think I got all four endings, but it would have been much better if the game had a counter of how many endings you have achieved. Could be an inner counter within game but the best way to do this would be medals on Newgrounds for each ending. 5 points for bad endings, 10 points for average and 25-50 for the best.
I can see how this is about the addiction, but is the second girl that protects the protagonist from lapsing back wit the one-night stand girl better somehow? Do they have some stable productive relationship? It is not explained in the game enough I think. And is substituting one addiction with other the same thing? Can he be free independently of her? If the friend leaves would protagonist lapse back to one night stands? The way I see it if someone still needs an outside influence to keep them clean then they are still addicted. Freedom is a choice and is independent of whether or not you have supporting friends, supporting family members or supporting religious group or a sponsor or any other kind of savior. No one can really protect anyone else from bad decisions without it ultimately not becoming coercion, it must be inner choice of full responsibility.