Blame Twitter for Jennifer Aniston and John Mayer's most recent breakup. The actress dumped her on-again-off-again beau over his obsession with the site, the Telegraph reports. “Jen was fuming. There he was, telling her he didn’t have time for her and yet his page was filled with Twitter updates," a friend told Star. "She was like 'He has time for all this Twittering, but he can't send me a text, an email, make a call?'"