Funnel Neck Pleated Woven Top

I'm 36D-29-38 and decided to size down to Small for a more fitted silhouette. The top looks fantastic, very flattering to the bust and waist. My problem is these torn-looking armholes! They are raw-cut with no reinforcing seams or seal, and as I moved around in the top, the pleats started accordioning wider, revealing a very ragged cut (see photos). So, it looks as though the fabric is torn or coming apart there. I'll try trimming down the ragged edges, but I'm worried it will develop new "tears." For now, I plan on wearing this top under blazers. I owned a very similar accordion top years ago that did not do this - not sure why the armholes weren't sealed in some way to keep the polished look.