Scientists and doctors have done a great deal of research over the last few years since it has become legal for medicinal use and in some places for recreation, and have found that marijuana IS NOT physically addictive in any way shape or form. A person who suddenly stops smoking marijuana after heavy use for a period of time does NOT go through any kind of physical withdrawl symptom. As Harry noted though, there could be mental issues to deal with, but a person can become mentally addicted to anything.............shopping, exercise, gambling, their phone, etc. And, I'm not going to discount your account of what you saw in your relative, but are you sure that marijuana was the only substance she was using? Because her withdrawl symptoms sound a lot more like alcohol use than marijuana.
I'd spent the last 8 years of my military career as a Drug and Alcohol Program Advisor in the Navy, and with all the information I'd been given concerning various substances, I could never figure out why they said marijuana was dangerous, because compared to other things, it seemed almost benign. So, after I'd retired and started to indulge, I decided to try an experiment on myself. I spent a month (a full 30 days) of using cannabis on a fairly heavy basis, consuming it throughout the day from when I woke up until I went to bed (I was retired, so my time was my own and I didn't have any obligations that needed to be met), and on day 30, suddenly stopped and went a week without partaking at all. Know what I noticed? First, that I was no longer stoned, but that was it. No shakes, no jitters, just that my mood was no longer elevated and I was normal. Didn't even feel a need to go get some (jonesing) either, just that I was back to normal.
I did notice however that when I went back to smoking it a week later, that the one week hiatus had resulted in the first couple of times I resumed that I felt just like I did when I first tried it.
No. Marijuana is not physically addictive. As a matter of fact, there have been several studies done where it has actually showed to be helpful in weaning people off of other substances like alcohol and heroin, so much so, that in many places it is considered to be an accepted treatment for addiction to alcohol and heroin.
Try that same experiment with alcohol, and you'd better make sure you have someone on call who can help you out when you stop, because you WILL experience DT's, nausea and shaking.