People claiming to be friends of the actress have told Star magazine that she finished the affair after discovering Mayer, 31, spent hours on the networking website, despite telling her he was too busy to get in touch with her.
A source claimed Aniston decided Mayer was not committed enough to her and called time on their romance having found hourly updates on his Twitter page.
The source said: "John suddenly stopped calling her or returning her emails and when she would finally catch up with him, he'd say: 'I've been so busy with work. I'm sorry I haven't had time to call you back."
The source added: "Jen was fuming. There he was, telling her he didn't have time for her and yet his page was filled with Twitter updates.
"Every few hours, sometimes minutes, he'd update with some stupid line. And in her mind, she was like 'He has time for all this Twittering, but he can't send me a text, an email, make a call?'."
It has also been claimed musician John made no attempt to cover up his Twitters.
The source said: "He didn't even deny it. He knew he was avoiding her. So when she called him on it and ended things, he just said OK, and that he was sorry it didn't work out.
"He took the break-up like a man." Even so, shortly after Aniston's call, Mayer's Twitter update read: 'This heart didn't come with instructions.'
True or not, this is hilarious.