It appears to be rubbing on something to cause only one side to fray. Has the alternator and/or the A/C compressor ever been changed in the life of the car? Just wondering if one of those isn't quote right for the car, so the alignment is off a bit. Or if one of the pulleys (alternator or A/C compressor) maybe has more or fewer ribs that what the crankshaft pulley has. Or maybe one of those pulleys (or the crankshaft pulley) was damaged at some point in time (such as when doing a timing belt change), and the belt is being worn due to a pulley made defective by removal or some other reason.

 

Could also be pulley misalignment. See Gates tech tips #8:

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As far as belt squealing goes, besides proper pulley alignment, make sure the pulleys are free of oil (I use an old toothbrush and alcohol to clean), and that the tension is correct. Gates has a simple gauge to help adjust the tension.

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AutoZone does sell the wrong parts. I've had it happen to myself and I know others who were sold wrong parts by AutoZone.

 

A simple test. Belt squeal? Turn off the AC. Belt squeal goes away.
This is what is known as a clue.