The womanising rocker - who has previously dated a bevy of famous women including Jennifer Aniston, Cameron Diaz and Jessica Simpson - thinks the `Firework` hitmaker is "the one" for him and he is keen to move in with her as soon as possible.

A source told HollywoodLife.com: "John wants to take his relationship with Katy to the next level.

"He has suggested to Katy that they get a place of their own. He feels like she`s the one for him and wants to commit himself fully.

"John is really into architecture and wants to create a `sanctuary` for himself and Katy."

The couple have been dating for six months and for Christmas, 35-year-old John presented the pop star - who was previously married to Russell Brand - with a custom-designed guitar to show his love for her.

A source said last month: "John has put some serious effort into his Christmas gift for Katy.

"Since they met he has been trying to prove he isn`t the guy everyone says he is.

"This should definitely prove that - every little detail on the guitar shows how much he thinks of her."

The musician had the guitar covered in intricate designs, including 28-year-old Katy`s initials and the date they first met.

The couple - who had a brief split last October before getting back together - are smitten with each other and like to spend every moment they can together.

One source said: "They are together virtually every day.

"They hang out at John`s place, cooking, watching movies and playing music.

"They take the odd trip away but generally they`re trying to keep it behind closed doors."
sections: Celebrities