Gwen Stefani's romance with Blake Shelton is ''better than ever''.

The 'Hollaback Girl' hitmaker recently rejoined the coaching panel on 'The Voice' to replace Adam Levine, and sources say she's been having the ''best time'' on the show - which she previously worked on for three separate seasons - especially thanks to her boyfriend Blake, who is also a coach.

An insider said: ''Gwen and Blake have been having the best time while shooting 'The Voice'. They laugh so much on set and backstage, and aren't shy about showing their affection and are better than ever.''

Gwen, 49, is ''happy to be back'' on the singing competition, and the source says her relationship with Blake is ''so different'' from when they first worked together on the panel - which is completed by John Legend and Kelly Clarkson.

They told 'Entertainment Tonight': ''Gwen seems secure and happy to be back. Their relationship is so different from when they first started dating on 'The Voice'. They're truly like a married couple who hasn't lost that spark.''

Meanwhile, 43-year-old country star Blake recently said he was sad to see his friend Adam leave the show after having coached for all 16 seasons.

He said: ''I didn't expect it. I didn't expect Adam to pull the trigger like he did. ... We all knew he was getting to the point - it was 16 seasons he had been doing the show, and it's hard to keep him focused on anything. He was ready to move on. ... I was pretty upset that Adam was gone.''

And although he said having Gwen on the show will ''soften the blow'' of Adam leaving, he noted the dynamic will be different because he ''can't go head-to-head with Gwen'' like that he did with the 'Sugar' hitmaker.