I'm writing a story in which a character's biggest flaw is their selfish desire to maintain a comfortable lifestyle. They've roped a young woman into being a maid who looks after the house in her spare time. She's naive, filial, and believes the best in others. There's a young man interested in marrying her and she's interested in him as well. The suitor is a sturdy, no-nonsense type who resents the main character for taking advantage of the woman's kindness.
My main character decides to sabotage this budding relationship to maintain his status quo. He tells the woman a lie that poisons her view of her would-be suitor. I'm stuck on what kind of lie he might tell. Any ideas?