Horribly long primary ferment

I am trying to cut back on the beer but still wanted a quick turnaround brew so I had something to drink every few weeks while all my big batches age etc. yada yada yada.

I picked up 10 of those cheap fruit punch concentrates from the store and did a 5 gallon batch using some brown sugar and honey to take the OG up to only about 1.055 and then pitched montrachet. The plan was to do like a 2-3 week primary and then bottle carb for a week and hopefully get something fairly low abv and drinkable... like a wine cooler or something.

Here we are 4 weeks later and its still bubbling... what the? I don't want to bottle it because its still putting off enough gas that I am guaranteed bottle bombs if I do. I haven't really had anything vigorously bubble for more than 2-3 weeks. Heck, I started a new banana wine just 2 weeks ago and its ready to move to secondary already. I can't figure out whats up with this brew and I want that primary vessel back!

Slow ferment can be due to low nutrients, low temp, ph, lack of oxygen, alcohol tolerance of yeast etc.

If your concentrate had any kind of preservatives in it that could retard the fermentation process.