On our fifth wedding anniversary, Nathan Lawson's first love sent me an intimate photo of them. He had one arm around Vanessa Reed's waist, and she leaned against his chest, smiling at the camera as if she had already won.   A moment later, Nathan called. "Vanessa says you've started taking cases where you persuade the other woman to walk away." He gave a soft laugh, as though none of this mattered. "She keeps pushing me to choose between the two of you. You're good at talking people around, aren't you? Convince her to accept things as they are and stop making a scene. How much do you charge?"   After a brief silence, I said, "50,000."   A notification from my payment app chimed. You received $50,000. The transfer memo contained only four words: Talk Vanessa Into Leaving.   I stared at the memo and smiled. This time, I didn't cry or argue. I accepted the case and signed the divorce agreement.   Nathan assumed I was only upset. He didn't learn until much later that Vanessa had left on her own and that I had disappeared from his life just as completely.   The next time I saw him, rain was pouring down. He knelt in the flooded street with red-rimmed eyes and begged me to take him back. I linked my arm through another man's and walked straight past him.   "Mr. Lawson, case closed. I don't do follow-ups."