Isn't this just BS, physiologically speaking? I have never heard of SSRIs increasing dopamine levels. Wikipedia even claims the opposite: "It is believed that sexual dysfunction is caused by an SSRI induced reduction in dopamine."
2. The concept of addiction is hard to define, and is becoming more so. Some drugs (marijuana springs to mind) can be considered addictive, but don't seem to cause the unthinking crave-gratify-repeat cycle you see with cocaine or nicotine. Some have argued that checking email or Facebook, playing MMORPGs, and "consuming" pornography are addictive.