What is the ruling on the words of the spiritual shaykh who told the questioner that he was afflicted by the "lover jinn" (qareen al-ashiq), and that he would not succeed in his life and would divorce his wife?

The One who brings benefit and repels harm is Allah alone. Therefore, you must rely on Him and have a good opinion of Him. Do not pay attention to the words of anyone who claims to know the unseen, because no one knows it except Allah. Strive in supplication, remembrance (dhikr), and the prescribed ruqyah (definition), and continue to consult trustworthy doctors.