Katy Perry and John Mayer 'heading for marriage'

Katy Perry and John Mayer are fully committed to each other and are headed for an engagement, it has been revealed.

A source has said that it's just a question of when the 'Gravity' hitmaker will propose, Us Magazine reported.

The insider added that the couple have realized that they must be together, while another source has claimed that Perry and Mayer skype and text all day.