Gwen Stefani and Blake Shelton's relationship appears to be going from strength to strength as the two were recently seen being playful and affectionate with each other in an episode of "The Voice."

On Monday, Dec. 7, the No Doubt frontwoman took to Twitter and posted a picture of her, Shelton, and their fellow "The Voice" coaches Pharrell Williams and Adam Levine. In the photo, the couple is flanked by Williams and Levine while the country star pretends to take a bite out of Stefani's shoulder. The "Used to Love You" singer captioned the shot, "@NBCTheVoice!! @adamlevine @Pharrell @blakeshelton gx."

Meanwhile, People reports that the couple has become more comfortable with openly showing their affection for each other as an onlooker who was at Monday night's live show told the magazine that Shelton even kissed Stefani on the set.

"Blake came up to Gwen from behind and kissed her on the head," said the eyewitness. "It was so cute! She turned around looking semi-shocked that he did that."

Another onlooker told Us Weekly that the pair spent several commercial breaks together on Monday night and were seen whispering and laughing throughout the night.

But that wasn't the only instance that the couple showed their fondness for one another. Us reports that after Shelton performed his new single "Gonna," Stefani gave him a standing ovation.

The two began dating in early November, months after Stefani ended her 13-year marriage to Gavin Rossdale. Shelton and Miranda Lambert announced their divorce this summer as well after four years of marriage.

While Stefani and Shelton have yet to talk openly about their relationship, the "Hollaback Girl" singer has expressed her support for her boyfriend on Twitter as she recently congratulated him for winning CMT Artist of the Year.

Stefani posted a congratulatory tweet on Dec. 3 and wrote, "Congrats @blakeshelton #cmartistoftheyear #michaeljacksonofcountrymusic."