If the letter of intent was explicitly non-binding, it should not have created a contract. That means then that so long as you did not--knowingly misrepresent anything of material significance (i.e. lie about anything important) to the tenant to get it to move ahead on the rental, or similarly did not knowingly omit to state anything which a reasonable landlord would have stateddid not outside of the LOI create any agreements with the tenant--you should not be liable to them for anything: sometimes negotiations prove fruitless, and so long as there was no agreement or contract in place and no fraud (material misrepresentations or omissions), there should be no liabiltiy.That said, the above is just a general principal: the specific facts are critical to a case like this, including the specific language of the LOI and other communications. You should review these things in detail with an attorney. Good  luck.