KOURTNEY: WHY MY MARRIAGE WILL LAST - and My Sisters' DIDN'T

A year after exchanging vows with Travis Barker, Kourtney Kardashian is still on cloud 9!

April 5 marked a special anniversary for Kourtney Kardashian. "One year ago today, an Elvis impersonator married me and Travis Barker after the Grammys and way too much tequila in a chapel in Las Vegas!" the reality star, 43, recalled to her Instagram followers. "One of the best nights of our lives, dreaming of a lifetime filled with fun adventures together."

That "lifetime" hasn't worked out for her younger sisters, Kim and Khloé Kardashian - who have a combined four divorces under their belts - but Kourt is confident things will be different with her and Travis, 47. "She knows it will last because, unlike with her siblings' marriages, she was friends with Travis forever before she tied the knot with him," says an insider. "Kourtney says that's their 'secret sauce.""

HAPPILY EVER AFTER

In fact, Kourtney's so confident in her union, she and Travis agreed to an April 13 Hulu special, Til Death Do Us Part, about their three ceremonies the unofficial Vegas vow swap, a courthouse affair in Santa Barbara and a glamorous wedding in Portofino, Italy. "This is our personal archive footage that we are sharing with the world," Kourt revealed.