Blake Shelton's relationship with Gwen Stefani "still feels new"

He told People magazine: "It honestly does [feel like time is flying by]. Some of the things that we talk about, we're to the point in our relationship that it's like, 'Oh, remember what happened...' and you realise, 'Oh my God, that was eight years ago!'

"It's like, how did this happen so quickly?

"10 years is a long time [but the relationship] still feels new for me.

"I feel like that might be the key to happiness, is that it feels just as exciting and new and happy."

Although Blake is currently promoting his new album, 'For Recreational Use Only', he is looking forward to a family summer with Gwen and her sons Kingston, 18, Zuma, 16, and 11-year-old Apollo - whose father is Gavin Rossdale - though they haven't yet made any plans.

He said: "I'm looking forward to the kids being out of school. Gwen and I pretty much have our summers wide open. We both have a few shows here and there, but nothing that's tying us down to keep us from going and doing something fun.

"We don't have any plans - which is our favourite plan."

Gwen, 55, appears on 'Hangin' On' on Blake's new album and he admitted they spend "months" talking about their collaborations, though she is "way more particular" about lyrics than he is.

He said: "We live together, so we walk around the house singing these songs all the time and we have months to talk about, 'Hey, maybe you jump on that part.'

"By the time we get to the studio, we're normally really prepared.

"Gwen is way more particular when it comes to a lyric. I've never been as much of a stickler as she is. It's really important for her to be able to see herself in the lyric that she's singing vs. me. I've sung about going to prison, and there's never really been a debate."

The pair recorded another track but have decided to hold it back for Blake's next record.

He said: "We were both so fired up about both of them that we ended up holding one back for the next project."