Simple idea, simply let us return a property without having to wait for the rental period to run out. Just means that we can return loaned properties to friends if we manage to make enough money to buy our own property :)
Also been suggested by Shak:
I would expand this suggestion to allow the renter to send an event to the owner being able to extend the current lease. I regularly rent to the same people so why cannot they just send me an event saying they would like to extend for the same price and same period. Similar to a trade they enter the days and price and you accept or not being the owner.