I really like the theory the horcrux affected Ron to the point where he left, was not because Ron was weak, but because the horcrux tried to weaken the trio the most by hitting them where it would hurt.

Ron provided the support and comfort that Harry and Hermione needed, and in order to protect itself the horcrux exploited the trio’s weakness. The horcrux sensed that Harry and Hermione would be weaker without Ron, and it worked extra hard to drive Ron away. It did that by amplifying its effects when Ron would wear it. That’s why Ron felt worse when it was his turn to wear it and that’s why he ended up leaving. The effects were that much worse for him, and in turn both Harry and Hermione’s morale was lowered without Ron.

Ron is probably my favorite from the trio and I hate how the movies did him dirty. That’s why I appreciate this theory.