Jill admitted she felt she "had no other choice" but to dump Paradise's Tarzan, who showed up to the beach with a big leaf covering his private parts.
"I literally had no other choice. I had to do what was best for myself," Jill explained. "There's just a line and, like, standards that you have for yourself that you just can't allow people to cross."
Jill said she and Jacob had started talking three weeks before the reunion taped on November 4, and in that short amount of time, they were "struggling."
"After our one-on-one aired, we were like, 'Ooh, we're catching the feelings again!' And then we started talking more and more," Jill recalled.
"I wish I had tried to pursue us as just a couple... an actual relationship where we could be just talking and having fun with each other... I kind of do wish that I at least continued things," he said.
Jill shared on the podcast how about three weeks before the reunion, she and Jacob were on the same page.
"We decided that we probably wanted to give this a shot, so we were just going to talk and try it out," Jill said.
"And then he made that grand gesture at the reunion, which was just kind of solidifying things. It was, like, my fairytale moment."
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At the reunion, which aired on November 22, Jacob asked Jill to give their relationship another shot. When she agreed to try, he swept her off her feet and carried her offstage -- and Jill appeared smitten and ecstatic.
As for what went wrong after that point, Jill revealed, "The trust had been broken. In a long-distance relationship, you need communication and trust, and we had neither of those things."
The architectural historian from Scituate, RI, said of Jacob, a mortgage broker from Scottsdale, AZ, that "he really fumbled the bag!"
Jill suggested the breakup was annoying for her because she "never wanted" to make her relationship with Jacob public to begin with.
"I just wanted to keep everything private, but the gesture happened at the reunion. We were like, 'Alright, we're gonna go forth and conquer,'" Jill noted.
But instead of conquering, Jill and Jacob's relationship crumbled.
"We had planned a trip to [visit my native] Rhode Island and everything. It was going to be really cute," Jill said. "But then unfortunately, everything kind of just fell through. Like, immediately after he hard launched it. So, ugh, it's so tough. I hate it."
Jill, however, said she has no hard feelings toward Jacob after their split.
"I don't wish ill will upon Jacob," she insisted. "I think that in the future, he could be a good partner to somebody if he puts in some work. So yeah, hopefully he will do so and somebody will be right for him."
Jill and Jacob were friends on Bachelor in Paradise before sparking a connection. They were known for having similar fun, quirky and outgoing personalities, and they really hit it off during a date -- during which they both got naked -- on the show's eighth season.
But during "The Split" twist, Jill was whisked away to a hotel with her girlfriends and Jacob developed a crush on a newcomer, Kate Gallivan, on the beach. Kate, however, diverted her attention away from Jacob and onto Logan Palmer.
Once Jill and Jacob reunited after "The Split," Jacob confessed that Jill probably wasn't his "person" considering he was able to move on from their romance quickly and catch feelings for Kate. He therefore ended their relationship and Jill left Paradise brokenhearted.
Jacob ultimately departed Paradise as well, alone and single, when the ABC series filmed in June.
Now that Jill is back in the dating pool, she joked that "the bar" is set "literally on the floor" following her relationship with Jacob.
"I don't want to say I'm embarrassed, because unfortunately the hard launch happened and it is what it is. And now I have to speak on it. I never wanted a public Notes app request for privacy. That is so lame! I don't want to do that," Jill complained.
"It is what it is," she concluded. "We're going to move on."
Jacob memorably told Gabby Windey that she's "smoking hot" but he only connected with and wanted to date Rachel. He therefore said if Gabby was the only The Bachelorette star, he would've sent himself home. Jacob later called his comments "ignorant" and apologized.