Kourtney Kardashian and Travis Barker are head over heels in love with each other, said an insider close to them.
According to the source, although the Poosh founder "was never opposed to marriage" before getting together with the Blink-182 drummer, "her thoughts definitely changed when she and Travis became official. Those two spend all their time together and are madly in love."
The couple surprised their fans after announcing they have gotten engaged in a dreamy proposal by Barker.
"She's over the moon," the source continued. "They're almost like high school sweethearts all over again. Neither of them ever thought they'd fall in love like this again."
One of the reasons Kardashian is so smitten with her fiancé is because of the way he treats her children, Mason, 12, Penelope, 9, and Reign, 7, whom she shares with ex Scott Disick.
"He's so sweet and loving towards her and her children," the insider told PEOPLE. "Their families also blended easily and nicely, and they all get along so well."
On October 17, Barker went down on one knee and popped the big question to Kardashian.
"Travis took Kourtney for a walk, and you could tell that she wasn't sure what was going on when she saw all the roses on the beach," a source told PEOPLE at the time. "Red and white roses were shaped into a heart. There were a lot of candles. They both looked very happy."