http://archiveofourown.org/works/320403/chapters/515251
Is this the story you're looking for? I think I'd read it a couple of weeks ago, and the whole cowboy thing I recognised too... This is on Archive of Our Own, though!
Author's response
THAT's IT! Thank you so much! I actually read it on a different site, but it's the same story so doesn't really make a difference! Thank you again!
Sx