ABC's 'Bachelorette' just made a surprising husband pick in the season finale that had every fan's jaw on the floor

Warning! Spoilers ahead.

The season finale of ABC's "The Bachelorette" aired Monday night and it was nothing short of jaw-dropping for the millions of fans who tuned in to watch.

Bristowe, a 29-year-old spunky brunette from Canada, had her pick of 25 men. She widdled down the pack to two suitors, Shawn Booth and Nick Viall, for the Monday night finale. Both men met her family during the episode, and both men walked away with engagement rings picked out.

Viall was presented as the sure winner. He and Bristowe were intimate early on in the season while there were still half a dozen men remaining. Her family loved him. And Bristowe commented multiple times that she loved him too.

But when he stepped out of the limo and embarked on a giddy, minutes-long proposal speech, Bristowe listned intently - then delivered a shocking blow.

"You look really beautiful," Viall began while Bristowe held a smile.

"I woke up today just thinking about this whole process," he continued. "We started talking and had no expectations and how quickly things turned into something more. Every moment I've spent with you since I've been here has been better than expected."

With Bristowe still beaming up at him, he continued. "I don't want to let us go because I am in love with you and I look at you and I have so much confidence in you and in us and I am yours forever if you'll have me. Caitlin..."

That's when Bristowe finally stopped him from getting down on one knee.

"Oh God," she muttered twice. Then after a long five-second pause, she explained her "heart was with someone else."

If getting dumped on television in front of millions of viewers isn't bad enough, Viall has now put himself in that same position twice. He was the runner up on last year's season of "The Bachelorette" too, and he returned this year to pursue Bristowe because he felt sure this time there was a serious spark.

But that spark apparently wasn't as strong as the one Bristowe felt for Booth.

Viall said he felt like the world's "biggest joke" during his exit interview.

Fans weren't thrilled with the way Bristowe seemed to lead Viall on and they blew up at her on Twitter. But they piped down when Booth made his entrance.

"From the moment that I saw you when I stepped outside that limo that first night I knew my life would never be the same," Booth told Bristowe. "When I went to introduce myself and you grabbed my hands I felt something I'd never felt before. I felt like I was exactly where I needed to be."

This time, Bristowe responded with some romantic lines of her own.

"Sean, the moment you stepped out of the limo I felt something for you that I can't describe and I don't think I've ever felt before," the bachelorette said.

"The truth is you light me up and you make me laugh and most importantly you allow me to be myself. And I know this has not been easy on you. Definitely we have had ups and downs and I've made some mistakes. A lot of mistakes," she said, alluding to her intimate moment with Viall earlier in the season.

"And I have be honest with you and tell you the truth. And the truth is that I never want you to question what we have ever again because I am completely yours and I will always be faithful to you and I've been waiting so long to tell you how I feel because I love you with all of my heart like I've never loved anybody before. And I can't wait to make a lifetime of memories with you and only you because you are the one and always will be."

Booth then proposed to Bristowe and she said yes.

It's been a few weeks since the final episode was filmed, and the pair appeared happy and in love on ABC's "After The Final Rose" episode Monday night.