3. They Are Using Drugs or Alcohol Excessively
To put it simply, no one can be a good friend while they are actively addicted to drugs and alcohol. Having a few drinks on the weekend is one thing, but daily use of illicit substances is another. Use of these substances depletes a person’s ability to be caring, aware and selflessly interested in your life. Addiction turns everyone into a means to an end, and you will become just another person to help them on their path towards self-destruction.
Certainly, abandoning someone in the grips of addiction is not very kind, but you must find the point that you can no longer commit your time, efforts and resources into someone that is not interested in improving their ability to be a good friend. Do what you can to assist them within reason and then move forward with your happiness.