 On Friday, 21 August 1970, the three Gibb brothers announced they would reunite and start recording together, nearly 16 months after Robin quit the group.They said later that they wrote "Lonely Days" and "How Can You Mend a Broken Heart" at their first reunion session, but the exact day when they recorded the song is unknown.However, a tape of stereo mixes received at Atlantic in October bears the tantalizing notation "August 20, 1970" which, if true, means the brothers announced the reunion the day after it happened.