Tenants want to break lease with 2 months left

My first furnished finder guests want to break their lease 2 months before it ends. They have been good guests and have already paid me in advance. They originally booked for 3 months, and we agreed to a signed 3 month lease agreement. They advised they were given a great opportunity that they could not pass up in Las Vegas and want to be out by September 1st. They did say they did not expect to get the full 2 months back in return, but I'm willing to work with them. Would like to know if anyone else has been in this situation and how they handled it. Thanks