and  are engaged! The rocker in Montecito, California, and a source tells ET the pair couldn't be happier about taking this next step in their relationship.

"Kourtney and Travis are over the moon. Getting engaged was always their natural next step and they are so thrilled," the source says. "The proposal was gorgeous and romantic, and everything Kourtney wanted."

According to the source, the proposal went down in a place with special significance for the two of them.

"The proposal took place on the beach at the Rosewood Miramar Beach hotel, where Kourtney and Travis have spent a lot of time together, and is considered to be a very special and sacred place to them," the source says. "Their families are beyond happy and excited for them too. Their kids are very much looking forward to being an official big happy family."

"Kourtney and Travis really feel like they've found their perfect partner and match," the source shares. "They can't wait for this next step in their journey as a couple and to spend the rest of their lives together."

Barker popped the question as the sun set, inside a heart made of red roses and lined with candles.

Kardashian confirmed the news on Instagram by sharing photos of the romantic proposal, which she simply captioned, "Forever." Barker also commented "Forever" on the post, along with an infinity symbol emoji.

Kourtney, 42, and Travis, 45, have been longtime friends and neighbors, and  

The two quickly got serious,  with their respective kids. Kourtney shares three children -- 11-year-old Mason, 8-year-old Penelope and 6-year-old Reign -- with her ex, . Meanwhile, Travis is dad to two children with his ex-wife,  -- 17-year-old Landon and 15-year-old Alabama.

The two also haven't been shy about . The Blink-182 drummer even , and Kourtney later on his arm.

A source told ET in May that the couple had discussed , and that the Kardashian family approves of Travis.

For more on the cute couple, check out the video below.