The guitarist is rumoured to be close to proposing to his girlfriend - who he has been dating since June 2012 - and already referred to her as if they were married when backstage before a joint appearance on TV show 'Good Morning America' on December 17.
An insider told Life and Style magazine: ''He kept calling Katy his wife. He said things like, 'I just do whatever the wife says' and then both of them would laugh. It was like looking at an old married couple.''
Friends say John has even been asking Katy's friends for tips on what type of ring would suit her.
The source added: ''He's serious about proposing to Katy very soon. He's been asking her friends what kind of ring she would like.''
During their interview on 'Good Morning America', Katy talked about how they are constantly working on their relationship, and admitted they have their ups and downs.
She explained: ''Relationships are kind of like riding a bull. You hang on for dear life. Sometimes you get a little buck here and there and sometimes you get things thrown at you but you get back on.''
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