For everyone trying to delete the message history:
I know this is a pain in the rear-end, but I found a way that works as a temporary fix.
~Write down the number of the contact you're trying to delete from the history (ex girl/boyfriend, secret lover, whom ever)
~Delete the contact
~Re-enter the contacts info
You'll notice the history for that contact is gone and even though this is a rather long route to take to delete the history it works.
Now lets just hope there's an update soon.