Back in the day disassociation wasn't an option. You wanted out and for it to be a permanent goodbye without shepherding calls or elder "drop ins", then disfellowshipping was the only route to take.
I'd been tempted to call it a day for quite a while. My JW parents were of the disapproving type no matter what I did, so they were never going to be sorely missed apart from the biological connection. Family visits were spent mainly discussing my many failings and how I should be doing much more of this or that. My then wife was totally nuts and also quite violent, something for which elders frequently counselled me - for allowing her to behave in such an unseemly manner.
Most importantly though was that I'd begun to stop believing. Despite one or two half-hearted attempts to rally round, I eventually admitted to myself that I just didn't enjoy witness activities one little bit. Ministry work, meetings, taking Bible studies etc etc, I would just watch the clock until it was time to go home.
There were a number of things occurred for which I could have been disfellowshipped. Eventually I was booted for associating with persons who had been disfellowshipped previously.
My life improved immeasurably within a year or two of my leaving. I was tricky for a while, but I hung on in there, refused to wear a victim hat and sorted my life out for the better.