Gwen Stefani and Blake Shelton are ''so in love it's disgusting'', according to Adam Levine.

The 'Hollaback Girl' hitmaker and the country musician have been dating since 2015, and their close friend and Maroon 5 frontman Adam Levine - who stars with them both on US talent show 'The Voice' - has joked that their romance is ''gross'' because they're so affectionate toward one another.

He teased: ''They're so in love it's disgusting. It's so funny. They found each other at really interesting times in their lives [after very public splits]. It's really beautiful. Because it's in the public eye, a lot of people want to have their own bulls**t opinions about it, but I'm, like, there. I see it every day. I have a pretty unique perspective on it, and it's real, man.''

The 38-year-old singer admits he too is overly affectionate with his wife Behati Prinsloo - with whom he is expecting his second child, and with whom he already has 13-month-old daughter Dusty Rose - but joked Gwen and Blake's romance makes him ''vomit.''

He added during an interview with Howard Stern on Monday (30.10.17): ''I'm so affectionate and gross with my wife - this is a whole other level of ... vomit. They're so in love. It's really nice.

''I still tell [Shelton], 'I can't believe you get to be with Gwen Stefani.' It's just not f***ing right!''

Adam's comments come after it was reported that 48-year-old Gwen - who has sons Kingston, 11, Zuma, nine, and Apollo, three, with her ex-husband Gavin Rossdale - and Blake, 41, are reportedly trying for a baby.

A source claimed: ''They will get married one day but right now they are hyper-focused on getting pregnant. They believe there is still a chance for Gwen [to fall pregnant]. They are incredibly hopeful.

''Gwen and Blake started talking quickly about having a baby, but starting a family has not been easy for them. It's something that they really want and it's just not working out the way they wanted it to.''