Answer: "Beauty is a cruel mistress, is it not?"
Uri originally wanted to marry Stella, but when he is at her apartment, proposing to her, he finds his lucky painting there and thinks she stole it from him. He says this line, thinking he got so blinded by her beauty, he didn't even consider her as the traitor. Also, it's ironic, because when Stella and Uri were on Uri's boat, discussing business, it was Stella's catchphrase.