'The Bachelor' Finale: Sean Lowe Picks Catherine Guidici, Pair Will Wed 'Soon'

Sean Lowe proposed marriage to Catherine Guidici, sending Lindsay Yenter home in tears in the dramatic finale of the 17 th season of "The Bachelor" that aired tonight on ABC.

Guidici accepted the proposal and the sparkling Neil Lane diamond engagement ring that Lowe presented her at the final rose ceremony in Thailand.

"I love you, I do," Lowe said. Guidici replied she was "so grateful" to have met someone like him and said she couldn't believe she was engaged to him.

"This is the coolest day of my life," she said.

The night ended very differently for Yenter, who looked stunned when she met with Lowe and he told her he had given his heart to someone else.

"I have to say goodbye to you, and it's by far the hardest thing I've ever had to do because I know how incredible you are and I love you. That's the hardest part I love you, you know I do. I'm sorry," he said.

She told him it was OK, and asked: "Was it me?" When he assured her that it wasn't, she replied: "I really didn't see this coming. I'm happy for you, I'm happy that you found love, but I honestly can't image my life without you and that's something I'm going to have to figure out."

As Yenter was driven away, she gave in to her emotions and cried. She said she felt like "an idiot."

"I fell for it thinking that he's going to propose … this is not fair," she said.

WATCH: 'The Bachelor' Meltdown: 'I Can't Control My Eyebrow'

Guidici is a 26-year-old graphic designer from Seattle, and Yenter is a 24-year-old substitute teacher from Fort Bragg, N.C. Both women professed their love for him.

The women made it to the final two after Lowe, 29, eliminated 24 other bachelorettes who had been vying to win his heart on the reality show.

PHOTOS: The Women of 'The Bachelor'

This wasn't Lowe's first search for love. The entrepreneur from Dallas competed on season eight of ABC's "The Bachelorette," and was eliminated by Emily Maynard right before the finale.

At the beginning of tonight's show, Lowe's family visited him in Thailand to meet the two top contenders for his hand. He told them he could see either woman "equally" as his wife, and confessed that he still hadn't made up his mind about which woman he would choose.

He said Yenter's obvious love for him made him feel incredible, and she was the piece he'd been missing for so long, but he added that he was falling in love with Guidici and she meant the world to him. He said he hoped his family could help him get clarity.

RELATED: 'Bachelor' Bombshell: Sean Lowe Dismisses Tierra LiCausi

His parents, Jay and Sherry Lowe, each met separately with Yenter and Guidice, quizzing them on their feelings for their son.

The family meetings went very well, and Lowe's parents told him they believed either girl would fit well into the family, but Sherry Lowe had a word of caution for her son.

"It's got to be something you're so excited to do … or you don't need to be proposing to either one of them," she said of the choice he was set to make at the final rose ceremony in a matter of days.

When Lowe's family left, the bachelor had a final date with each woman. He took Guidici for a ride on an elephant, and went on a river boat ride with Yenter.

MORE: Desiree Hartsock Departs 'The Bachelor' After Hometown Date Drama

At the end of the date with Yenter, she was optimistic about the possibility of a future with Lowe, but Guidici was frustrated and discouraged by her prospects.

At the end of her date with Lowe, she finally told him that she loved him. He hugged her in his silence before replying, "Thank you for today."

Guidici was upset by his response, feeling that he had done little to indicate that he reciprocated her feelings.

Lowe got the chance to meet Guidici and Yenter again tonight on "The Bachelor: After the Final Rose." He reiterated his admiration for Yenter and his regret at breaking her heart, and she wished him well.

He said he and Guidici would get married 'soon' and the wedding would be televised on ABC. "The Bachelor" host Chris Harrison said the wedding would air this summer.

Also on the horizon for Lowe is a spot on the celebrity cast of "Dancing With the Stars." The former bachelor will pair up with professional dancer Peta Murgatroyd on the dance floor, following in the footsteps of past "Bachelor" contestants Jake Pavelka, who competed on season 10, and Melissa Rycroft, who most recently won last's season "All-Star" competition.