But to address G's original complaint: yeah, headphone ear pads do tend to come apart with age and use. It's not just you, and it's not just the synthetic. Sheep skin ear pads come apart, too. They just take longer. Most non-disposable headphones have replaceable ear pads for this reason. All three of the headphones that I mentioned have replacements pads, both synthetic and velour, for about $25 a pair.

Edit: there's also a simple ear pad mod known as the "sock mod". So called because it entails wrapping the cut off tops of some socks around the pads.