Answer:
Even though Luther was trying to obtain a long term contract with Martha's Tea Salons for a while, he is not responsible for them breaking apart. In order for wrongful interference of a contractual obligation (which is a tort) to exist, Luther must have actively done something to break their contractual relationship. Luther started an advertising campaign, but that does not directly interfere with Martha's and Harley's relationship. It is like saying that because Coke has a lot of advertising, if any of Pepsi's clients breaks up with them, Coke would be responsible for it.
Martha cannot be liable for wrongful interference, she might be responsible for breaching her contract with Harley, but that is something else. Depending on the specific terms of Martha's contract with Harley, Martha may or may not have breached the contract. If the contract allowed Martha to terminate it at will, then there is no breach, but if the contract was supposed to last a specific amount of time, then the possibility of a breach really exists.