In most instances with "deterioration" it means one of two things: Either the rug is actually deteriorating, or there was an improper balance of fibers in the structure of the rug. This carpet I cannot tell if it even has a warp, but presumably it does. Depending on how far surrounding the areas is affected, I would act accordingly. I don't
believe professional repair is warranted, as it's very cost-prohibitive. However, if the damage or problem does not go too far into the rows above or below, you could attempt stitching, but you really have to make sure what you're harnessing to is VERY solid, and usually this could be felt. To really repair it properly would be very intense. Most
good specialty rug repair people will base the quality of repair off the value of the rug. Given I do not know what the rug is, it
could mean a thorough reweave, or something as simple as latex glue and a small rectangle of burlap (I would not advise as this is not easily reversible). Bottom line is it's not advisable to use in moderate traffic as is as this parting/split could easily be breached even further
Sorry I can't be more specific... I do think the rug is worth every bit of the 30 you mentioned before. These kind of problems are not uncommon for this type of weave. Structure reminds me of a rag rug in the way it's separating. Personally I think the best option would be (provided the areas surrounding are durable), if you're handy with a needle and thread and hiding the work on the front, perhaps try? Just not familiar enough nor can I feel the extend of deterioration (if that's what it may be) to give the best go-ahead for any solution