Gwen Stefani is so smitten with Blake Shelton that she can't believe he is "real".

Gwen Stefani and Blake Shelton

Gwen Stefani and Blake Shelton

The No Doubt singer has taken to Twitter to gush about her country musician beau and praise him for his "amazing" new single 'Guy With a Girl', which is doing well in the country radio charts in America, and to tell him how "lucky" she is to know the 'God Gave Me You' hitmaker.

The 47-year-old beauty retweeted the hunky singer's tweet on the micro-blogging site, which read: "Wow!!! 'Guy With A Girl is #1 at radio!!! Thank y'all!!! Thank you country radio!! And thank you Warner Nashville!!! (sic)"

She then added: "How r u real!?! #uramazing #luckytoknowu #everyonelovesBS #guywithagirl ##1 Gx (sic)"

The 'Don't Speak' star - who has children Kingston, 10, Zuma, eight, and two-year-old Apollo with ex-husband Gavin Rossdale - was recently praised by her 40-year-old partner for being a "good human being with a great heart".

Blake gushed in an interview: "I love talking about Gwen, are you kidding me?

"It's been just an eye opener to be with someone like her. Believe it or not ... I mean, you think Gwen Stefani and No Doubt, and she is literally maybe the most normal person that I've ever met in my life. It's been good for me to be with somebody that's so grounded and just a good human being with a great heart."

And it isn't just the 'Used to Love You' singer's personality that Blake likes, as he also says she's nice to look at.

He added: "And she's hot. Have you seen her? I mean look at that!"