"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."
Travis popped the question as the sun set, inside a heart made of red roses and lined with candles.
Kourtney, 42, 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.
Blake Kirsch witnessed the proposal and told ET that "it seemed as though [Kourtney] knew what was happening" when she made her way to the floral arrangement.
"Kourtney seemed giddy and Travis and her were very touchy and cute. As Travis spoke, he was smiling and happy, but also serious," Kirsch said. "Before Travis pulled the ring out of his pocket, he was fidgeting with it a little and seemed a bit nervous. Kourtney was smiling, and seemed a little nervous too. Travis then got down on one knee to propose. Kourtney definitely seemed surprised, but didn't gasp or anything, and they kissed afterwards for a little while."
The two quickly got serious, taking family trips with their respective kids. Kourtney shares three children -- 11-year-old Mason, 8-year-old Penelope and 6-year-old Reign -- with her ex, Scott Disick. Meanwhile, Travis is dad to two children with his ex-wife, Shanna Moakler -- 17-year-old Landon and 15-year-old Alabama.