For some buyers, they infect the internet and it's not even about shopping.  They are so out of control, and insane, they actually invest in a relationship with you.  In the case that happened today, some insane jerk, complained about lighting in photos of an item I uploaded.  Instead of making a 5 or 6 word message, he ended up investing 48 hours and 7 or 8 lengthy message, that were off the rails crazy. 

For them and their own narcissism or whatever plagues them, they won't go away, and their issue is to try to invest emotions and triggers in people and "have the last word"  Only their "last word shows up in any sellers account as an unanswered question.  Ebay removed the option to "not answer" so it just stays there, and it's harassment of a bad buyer.  Start w/ blocking them, then invest in reporting them to Ebay, they can read every single message, and then copy yourself on the message so they go to email.  If the stalking still persists, you can file an internet stalking report on them, call the cops, or FBI.  People this toxic and obsessive just thrive on long contact, and abuse of the Ebay site.  Ebay is finally dealing w/ some of these predators that do lose their right to even use the site.