Peter Weber on His Unconventional 'Bachelor' Finale: Why It Won't Be Spoiled (Exclusive)

Fans might have to wait to find out what happened in that shocking 'Bachelor' flash forward.

The Bachelor is doing things differently this time around. 

Season after season, curious fans have used their investigatory skills to find spoilers on how each season ends -- but not this time. As Bachelor Peter Weber proudly told ET's Lauren Zima on Tuesday, he doesn't think anyone will be able to guess his season's ending. 

"There's a specific reason [it won't be spoiled]. Obviously I can't say [what it is, but] I feel like this a little bit unique of an ending," he teased. "I couldn't have predicted that last week was the hardest week of my entire life. Chris [Harrison] can tell you."

"The way this ends, no one will see coming. I can say that because we didn't see it coming," added Harrison, who served as Tuesday's guest co-host of ET. "The crew is beside the point. Peter and I, going through this together, had no idea this was happening and how this was going to all come to an end. So, it's riveting, and it really is breathtaking and it'll break your heart."

Weber previously told ET that "no one's going to find out the ending" -- leading some fans to speculate that he hasn't yet made his final choice. The Bachelor usually hands out his final rose at an exotic locale on the final day of filming in November, but some viewers think Weber might hand out his final rose closer to the show's season finale in March. 

"[Getting engaged] at the finale, at the AFR -- that's a good guess," Weber conceded. "You can't see this coming for a mile, so maybe. I don't know." 

Whether he's made his final choice or not, Bachelor viewers are in for a dramatic finale. The pilot's Bachelor premiere kicked off with a shocking flash-forward in which host Harrison gives Weber a "heads up" about something serious. The Bachelor's mom, Barbara, is also seen in tears, pleading, "Don't let her go. Bring her home to us!" 

"It's in the last week," Weber revealed of when that emotional moment takes place. 

"It's not comparable because it's completely unlike those stories the way it unfolds," Harrison said of how Weber's season finale stacks up against Colton Underwood and Hannah Brown's. "This will stand alone and be epic for a completely different reason. It's not for an athletic event or feat, and it's not for the topsy-turvy twists and turns that was Hannah. His is more of an emotional ride and roller coaster at the end."

So far, several women seem to have the chance to get to Weber's finale: Madison, Hannah Ann, Victoria F. and Kelley all made big impressions in the season premiere. 

"I lucked out with that date like no other," Weber said of his first one-on-one of the season with Madison, who accompanied him to his parents' vow renewal. "That could have realistically been a really awkward and uncomfortable date. That's a big thing, introducing [a woman to your family], of course when you're dating and the first date, but she absolutely knocked it out of the park, killed it."

"I was flying really high after that date," Weber recalled. "She definitely really got off to a really good lead. And you guys saw it."

Hannah Ann, meanwhile, earned the first impression rose -- after stealing the Bachelor away three times during the cocktail party.

"She stuck out to me so much, and some people, they have their opinions, but I love the boldness. I loved her being so intentional and showing me exactly why she was there. And I think it's important to note that she's the most sweetest person. She was doing it the right way. She wasn't being mean about it, or necessarily disrespectful to any of the women. She's the sweetest person and it worked, and I appreciated it," Weber shared. 

Harrison warned that Hannah Ann might find herself in some drama this season -- but not necessarily with Victoria F., whom he's previously labeled as this season's villain. 

"I felt horrible [that I forgot her opening joke]," Weber confessed. It's Kelley, however, who has the biggest target on her back after the premiere, after she and Weber strengthened their connection on the first group date. The two had previously ran into each other a month before filming started. 

"For sure going into this, I'm thinking, 'Is this some kind of fate?' Like, why did this happen?' And I didn't know if she was actually going to show up that first night. It was a pleasant surprise," Weber said. 

"I remember that conversation, we went out to the front step and it just felt so good because I kind of already knew her. We had spent an hour talking when I first met her the first time, so it just felt very comfortable and easy and it was good chemistry," he added. "We got along well."

The Bachelor airs Mondays at 8 p.m. ET/PT on ABC. See more in the video below.