My tenants are too good?!

[Meredith Mihm]

I think I have a problem I haven't read about... choosing tenants that are too good to last. My last two sets of tenants for our single family (I just found out about the second set today) have BOTH broken their leases to purchase their own homes.  Is it my fault for choosing people who are so responsible and have such great credit? Do you try to rent to people who can't afford to buy, or who have circumstances that make it unlikely? Both sets have approached us with the understanding that they are ultimately responsible, and the first set did pay for a month that it sat empty while we found tenants, but I would like to have someone living there for at least one whole year.