they cant leave you negative feedback just for not 
closing your auction early. its YOUR auction. you 
decide when if it ends early. If you dont want to, 
just explain to the person that you would rather 
wait it out.

You're doing nothing wrong by NOT closing your 
auction early. (unless you want to!!)
and again, if you choose to close your auction 
early, that's your choice, the bidders who are 
"waiting" know that you can close it early if you 
want, so its their risk not yours. :)