Simplify the following text for a Grade 5 native English-speaking person.
Original: Tristan was allowed to leave with the promise never to come back , but he later returned with the intention of marrying Isolde to his uncle , King Marke .
Simplified: Tristan had been allowed to go back to Cornwall . However , it seemed now he had told his uncle , King Marke , all about the beautiful Isolde and had come to get her so that his uncle could marry her .