EXCLUSIVE: Gwen Stefani Spotted at Blake Shelton's Recording Studio -- Just Cozying Up or Making Music?

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Are Gwen Stefani and Blake Shelton making sweet music together?

Shelton was spotted on Wednesday morning at the Los Angeles studio where The Voice coach training happens -- and he was joined three hours later by none other than Stefani. The 46-year-old singer arrived in a stylish red leather jacket, jeans, and a black t-shirt that showed off her flat stomach, and an eyewitness tells ET Stefani was in a hurry as she rushed into the studio.

WATCH: Gwen Stefani Bonds With Kourtney Kardashian, as Gavin Rossdale Steps Out Still Wearing His Wedding Ring

Shelton eventually left separately through the back door, but not before displaying his good mood. When asked how he and Stefani's relationship was going, the 39-year-old country star happily responded, "Going good!"

Obviously, the new sighting is giving fuel to their fans' hope that the couple is recording a song together. Earlier this month, a source confirmed to ET that the musicians have penned a song together, though it was unknown if they had recorded it yet.

Or perhaps the studio interlude was because the two were just looking to spend more private time together? Later that night, Stefani and Shelton met up once again to attend Barneys New York's private dinner celebrating jewelry designer Jennifer Meyer's exclusive ready-to-wear collection. The two mingled with their fellow A-listers at the event, which was also attended by Jennifer Aniston, Kris Jenner, Courteney Cox, Katy Perry, Nicole Richie and Chelsea Handler.

"Gwen and Blake seemed really happy," a source inside the party tells ET. "They were hanging together inside the party and near each other the whole time."

Stefani was snapped sporting the same white belt and jeans she was wearing earlier at the studio with Shelton, but changed into a white blouse and an eye-catching black jacket.

Getty Images for Barneys New York

Though the two weren't photographed together at the event, Shelton happily posed with actor Tobey Maguire, who's married to Meyer.

Getty Images for Barneys New York

WATCH: Gwen Stefani and Blake Shelton Serve Up Some Sweet PDA on 'The Voice'

The Voice coaches' relationships only appears to be getting more serious. ET recently learned that Shelton is close to completing his new home -- only an hour away from his hometown of Ada, Oklahoma -- and, in late October, he gave his girlfriend the grand tour.

"Blake gave Gwen her biggest taste of country life," a local resident and friend of Shelton's told ET. "They ate home cooking at his favorite diners and Blake took her to his new lake house. There's no Starbucks around here. If she's still around after that then it must be serious!"

For a look at the incredible home, watch below: