I'd like to think I went out with a nice bang.
I had been raiding with a new guild for about 4 months after my old guild collapsed between patches (that guild is still the one I'm the most fond of).
Every expansion I've ever played, I've changed my main class. I tanked as a warrior in BC, a paladin in WotLK, a druid in Cata, and a death knight in MoP. I figured as WoD was approaching, it was almost time to swap mains. I used my free 90 boost on my monk and got it to 555 ilvl in a week so I could start tanking normals (heroics now) instead of using my death knight. After a couple weeks I was ready for heroics (mythic) and we were progressing while I was tanking on my monk.
I don't know what it was, perhaps since I had so much experience raiding as a death knight; I wasn't really enjoying the monk. I wasn't great at keeping all my buffs rolling and I was used to handling all of these fights in a very different way.
Additionally, in a couple short months, I would be returning to school for my final year (I had a 16-month paid internship and a lot of free time prior) and I'd have to give up raiding in September anyway.
And worst of all for me was the recent decision to move to 25-man progression to prepare for mythic raiding in WoD. I tried a 25-man guild previously and didn't like it; the raids felt more empty despite having more people compared to a tight-knit 10-man group. That was the nail in the coffin for me and I wasn't having as much fun anymore.
So one night, spur of the moment, I went full rage quit... completely unplanned.
We were facing General Nazgrim and I didn't have shuffle up or something when he was using his tank swap ability and I got 1-shot, so I went for it.
I left the mumble server.
I guild quit.
I logged out.
I logged in on my death knight, guild quit on her, and logged out as well.
I went to our progression spreadsheet which we were using to track our main raid team and potential trials for our 25-man, and I added my characters' names to the "banned" list.
I didn't log on to WoW again until first semester exams finished in December.