the fundamental issue here is who does the lease protect and if the renter breaks the lease what can you do about it. if he breaks the lease by not paying anymore rent and or moving out he wins even if you take it to court you lose you may get a judgment for the lost rent but you are unlikley to ever collect.

if you really like the tenant talk to him find out what it would take for him to stay or where he thinks he can move to that wont have the same risk at the same rent level

other than that start looking for your next tenant NOW