I've heard that people tend to be more successful at keeping a heroin habit casual than cigarettes (this is where the infamous "cigarettes are more addictive than heroin" claim comes from). I have experience with opiates, but not with heroin specifically. I've heard that it is very similar to morphine or oxycodone, which I have been on while in the hospital and for an extended period after. These chemicals ARE powerful pain killers, but if you aren't in constant physical agony, and are using them to get high, they can have a profound impact on your life. You may be able to pass for sober and even function and hold job, but that shit effects you over time. Makes you unstable. My boss at my last job was a pill popper and she was almost too crazy to handle much of the time, even though I'm sure she thought that she was perfectly functional. You really can't judge that for yourself.
In my experience, people tend to break down mentally with prolonged use of any addictive substance. I've seen too many people go CRAZY on pills, alcohol, cocaine, and heroin not to speak out on this subject. I'm glad that you can keep your drug use casual, but I fear for your girlfriend, and for you by extension. When you talk about her attitude toward the drug I can't help but look back on my own past and the people who I can't have in my life anymore because drugs have turned them into untrustworthy, unreliable, unpredictable people capable of things I would have never thought possible. An addict will do ANYTHING: lie, steal, and cheat to get a fix. You may trust someone, but when they have a habit they are the drug, not themselves. In the words of the immortal Hunter S. Thompson: "You can turn your back on a person, but never turn your back on a drug, especially when its waving a razor sharp hunting knife in your eye."
