A friend of Boyle's told The Sun: "She wanted to go home as she was tired and upset. Susan is very sorry to anyone she upset."
The former contestant on the ITV talent show has had treatment at the Priory clinic in the past following public outbursts.
Police were not called to the scene. Boyle is due to tour with the show until October.
Meanwhile it has been reported that she could return to the show that she came second in four years ago as bosses plan to get her back to perform at the final.