Plot hole: an easy truth?
If Marie thought Zack had used one of those words to make her love him, couldn't she use a word to make him tell the truth? She could have compelled him to give her an honest answer and he would have done it. They already established with the government guy that using those words can make someone tell the truth. I don't see why she spent all that time distrusting him.
Read my short story, Cat's Milk.
http://mstrainj7.wix.com/mstrainjr