Inside Gwen Stefani and Blake Shelton's PDA-Filled Oscar Weekend: 'They Were Like Giddy Teenagers at a High School Dance,' Says Source

"I don't think either of them stopped smiling the entire time they were there," an onlooker tells PEOPLE

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From bonding with her boys to roughing it in his Oklahoma hometown, Blake and Gwen are forging love after heartbreak. Subscribe now for Hollywood’s most surprising couple’s love story, only in PEOPLE.

During Hollywood’s biggest weekend, Blake Shelton and Gwen Stefani were quite possibly two of the busiest stars around.

On Sunday night, the adorable couple hit the Vanity Fair post-Oscar party, posing together on the red carpet for the first time (and yes, Shelton still sported his cowboy boots while Stefani was dressed to the nines in a sexy red Yanina Couture gown).

“They acted like giddy teenagers at a high school dance,” says a fellow attendee. “They were holding hands the whole night and didn’t leave each other’s sides. I don’t think either of them stopped smiling the entire time they were there.”

Continuing their Oscar festivities, the duo also partied at Guy Oseary’s post-Oscar house party, where “they were cute as a button in a corner together,” says a guest. “She was glowing and he was charming. There was clearly a lot of love and happiness there.”

At a private event earlier in the day, the “Sangria” singer also wasn’t far from his girlfriend, who performed several songs, including her new single “Make Me Like You,” which she wrote about Shelton.

For much more on Shelton and Stefani’s romance and their plans for the future, pick up the latest issue of PEOPLE, on newsstands Friday.

“She owned the room,” says an onlooker. “Blake was just outside of the green room, and his smile was ear-to-ear. He clearly adores her and was just fixated on her. It was super sweet.”

The pair’s glamorous date night capped off a weekend of fun. On Friday, Stefani supported her boyfriend at his Kansas City concert, and on Saturday, the duo attended Shelton’s former Voice contestant RaeLynn’s wedding to financial advisor Josh Davis in Franklin, Tennessee.

“They were very low-key, affectionate and comfortable together,” says a wedding guest. At the reception, the stars – who first met on the set of The Voice in 2014 and began dating last November – “had their arms around each other and slow-danced to a song together.”

•Reporting by MIA McNIECE, SARAH MICHAUD and JANINE RUBENSTEIN