The actress - who split from the singer in April - is reportedly struggling to get over her old flame and has good luck messages delivered to John Mayer, the Gravity star's dressing room before he performs.A source told contactmusic.com: "Jennifer sent John a hand-delivered perfumed note before one of his concerts recently. It read, 'Play well, you always do'. It was sweet. Clearly she doesn't want to let go completely."
Friends of the 30-year-old singer claim Jennifer - who was recently romantically linked to her He's Just Not That Into You co-star Bradley Cooper - has stayed in touch with John's brother and a reunion could be possible.
The source added to Britain's Daily Express newspaper: "John hasn't shown any interest in other women since the split, which is a break from the usual pattern.
"Who knows, this may not be the end of their romance. Neither seems very good at letting go."