Joe Jonas and Sophie Turner announced their engagement on social media, Sunday

The Jonas Brothers — and wives.

Joe Jonas and Sophie Turner are engaged, and the singer’s family couldn’t be more welcoming to their new addition. “Everybody’s very, very happy for them and their family and friends are all thrilled. Everyone loves them together,” a source tells PEOPLE of the exciting news.

Adds the insider, “She’s young but is beyond her years and is crazy, crazy mature. He’s never been like this with a girl.”

“He was such a dater before her but their relationship was much different from the start. She was just the one for him.”

Credit: J. Webber/Splash News

The couple shared the happy news with corresponding Instagram posts on Sunday. They each posted an image of the Game of Thrones star with her hand on top of the singer’s, showing off the stunning engagement ring against their black clothes.

“I said yes,” Turner, 21, captioned the photo. Meanwhile, the 28-year-old singer wrote, “She said yes.”

The DNCE frontman’s brothers, Nick and Kevin Jonas, were among the first to congratulate the couple.

“YES!!!” Nick wrote, while Kevin similarly chimed in with, “Yeah!!!!!!!”

Nick, 25, then shared the photo of the ring on his own Twitter page to further congratulate the couple. “Ahh! Congratulations to my brother… and sister in law to be on your engagement,” he said. “I love you both so much.”

EXCLUSIVE: Joe Jonas and Sophie Turner enjoying the French Riviera
Joe Jonas (left) and Sophie Turner
| Credit: Splash News Online

Jonas and Turner have been dating since last November, after they were spotted acting cozy at a concert in the Netherlands — although the duo didn’t become Instagram official until January.

Since then, the couple has been going steady — they even share an adorable Siberian Husky puppy together named Porky Basquiat — and were recently snapped sharing some sweet PDA while out and about in Los Angeles.

RELATED VIDEO: Joe Jonas and Sophie Turner Spotted Getting Cozy in the Netherlands

As PEOPLE exclusively reported in June, a source close to the musician said that Sophie is “different from the other girls [Jonas] has dated.”

The couple have kept fairly tight-lipped about their romance. “I’m in a relationship, but it’s a very private relationship,” Turner told the U.K.’s Sunday Times in July.

“I very much isolated myself for a while and forgot what was fun. Going out with friends, going out to eat, not really having a care,” she told the publication. “And people I’ve met recently in my life have drawn me out of that.”

She continued, “It really helps you own those insecurities. The things I tortured myself about before, I can forget about.”

Sophie Turner and Joe Jonas Out with New Puppy Porky Basquiat
Joe Jonas (left) and Sophie Turner with their puppy in NYC.

According to the British starlet, she’s in a much more positive place in life than she was before. “I’m happier than I’ve been in a very long time,” she said.

Turner also opened up to InStyle this past spring about her high-profile relationship. “I found it easier to date someone who understands the industry or is in that world,” she said.