Fifteen years ago Katie Couric lost her husband, Jay Monahan, to colon cancer and raised her daughters on her own. Now Katie, 56, speaks exclusively to PEOPLE about the emotional proposal from her boyfriend of more than a year, John Molner, and why she never stopped hoping she’d wed again.

Last weekend, on a beach in East Hampton, NY, Molner, a finance executive, opened a bottle of rosé and began telling Katie how committed and in love he was. Katie remained unfazed. “I was like, ‘yeah, I know that. You didn’t have to bring me here to tell me that,’” she tells PEOPLE with a laugh. Finally, Molner cut to the chase. “Couric, I’m trying to propose to you,” he said, getting down on one knee in the sand. “I was stunned,” she says. “I had no clue! It took a long time for my brain to process what was going on.” Her groom-to-be, at least, is thrilled to have caught her off-guard. “I was very old-fashioned in how I went about the proposal,” Molner, 50, explains. “And it was a surprise to her. I was excited to catch her in a moment of confusion, which is pretty rare.” But Molner has been sure of his intentions for quite some time.

“Meeting Katie really changed my life,” he tells PEOPLE. “I’ve loved getting to know her and her daughters, and I couldn’t be happier. When she said yes, I was just elated. It was a great culmination to one of the best periods of my life.” Couric, still “gobsmacked” when she looks at her left hand, continues to swoon days later. “I’m a little overwhelmed. I have to take a moment,” she says at one point, clearing her throat. “It’s an incredibly special time.”

For Couric, the engagement is significant, and not simply for the heartfelt display of emotion. Fifteen years after losing her 42-year-old husband, Jay Monahan, to cancer, Couric admits that preparing for another wedding is bittersweet. “I had such a happy marriage. I loved my husband so much,” Couric says of Monahan. “It’s nice to finally meet somebody who has so many of the values that he had. That’s been a real comfort. I made sure to call Jay’s siblings – and he was one of seven kids – and they were all so happy for me. That made me even happier, that they were all so thrilled. It sort of feels like it gives me permission to feel the way I do now.”

Having raised daughters Carrie, 17, and Ellie, 22, on her own, Couric is now excited for the next chapter in her life. “The fact that we’ve been the Three Musketeers for nearly 16 years means that change – even a positive one – can be challenging,” she acknowledges. “But I think the overwhelming feeling is one of joy.” It’s a joy she’s waited on for a while. In the years since Monahan’s death, Couric made no secret that she “always wanted to marry again. In a way I’m surprised it took 15 years, but things happen when they’re supposed to,” she says.

Of course, every relationship has its challenges. Molner has two kids from his previous marriage, one in college in Colorado and one still in high school in New York. Couric has Carrie at home for one more year; daughter Ellie lives in California. “John’s kids are great, and he’s a very devoted father to them,” says Couric. “He’s also very respectful of my bond with my girls. I’ve done stuff with his kids; he’s very close to mine. We’ll let things fall into place naturally. It’s not exactly a Brady Bunch situation because our kids are at a different point in their lives.” A wedding will likely wait until Carrie leaves for college. “I want to get her off into the world and enjoy her last year at home,” Couric says. Molner, for his part, is happy to go with the flow. “There are family logistics to consider,” he says. “But I’m ready to go whenever called.”

More on Katie Couric is featured in the 9/16/13 issue of PEOPLE, on newsstands everywhere now.

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