Tenant wanting to break lease early, possible slight problem

[Eric Pollard]

Our tenants have an 18 month lease agreement that won't end for another 7 months. They want out early, not for any significant reason. Basically they realized they wanted to live closer to where they work (a job they had taken from out of state before signing the lease). The problem is we were going to sell the house at the end of this lease. I know if it remains a rental then of course they pay rent until we find someone new. However, selling could take months, possibly longer than the 7 months that remain on the lease. 

The laws that I am aware stipulate we have to make a reasonable effort to find new occupants. But we don't want renters, we want buyers. Is that still reasonable? Any insight would be appreciated.