Had to take off the top and bottom pulley from my E-thirteen chainguide today in order to remove the cranks. I reinstalled the crank, put the chain back on the chainring and went to put the pulleys back on the guide. However, for some reason the chainring was no longer centred in the guides (it was now too far towards the outside). I tried turning the cranks one revolution and the chain actually came off of the chainring from the excess pressure from the guides. I thought that perhaps the cranks were out a bit so I checked the spacing and it was the same as before I took them off. Am I missing something here? I'm sure I could just slip a couple small washers in between the chainguide backplate and the guides (both top and bottom) to get the alignment right but it was working prior to the crank's removal so it should in theory go back and work properly without any extras now.

Side note, this thing pissed me off so much today that I was tempted to shoot it... I'd rather fix this in a peaceful manner lol

Is it possible that you mis-remember the crank spacing and added a bit when refitting. Or maybe the spacer isn't fitted right to the chainguide plate, or the sequence is different, and the spacer used to be behind the plate (which I doubt, but covering the bases).

Either way go back and check your work. measuring from the tops of the sprocket teeth to the chainguide plate as a reference, and see if you can move the crank in the right amount. (or move the chainguide out).

By the same token, see if you misplaced a washer o something and mounted the pulleys farther in w/respect to the chainguide plate.

Your best bet, set the bike aside, have a beer and take a fresh approach when you're ready to think instead of just going at it.

If you have a square taper bottom bracket be sure that you have torqued the crank fixing bolts adequately. If not torqued enough the cranks will ride farther out on the tapers (and also be liable to loosen in use). Maybe you measured the crank position from a different reference point after assembly. Don't try to figure it out when you are angry; come back to it when you are in a better frame of mind.

I definitely need to go back at it with a more relaxed frame of mind.

The bb (Race Face X-type) itself wasn't removed, nor was the chainguides backplate. The spacing was measured by the gap between the bb cup and crankarm and it didn't change. There were also no spacers originally on the chainguide where the guides meet the backplate so none were put on during the reassembly.
This misalignment seems to be off by approx 3mms which is quite a lot and definitely more than any fraction of a mm that the crankarm might be off by now during the reassembly.