"With hometowns right around the corner, it gets really real," Zach told Becca Kufrin and Michelle Young on the March 7 episode of the "Bachelor Happy Hour" podcast.
"That's when families are involved, and it's not... traveling around the world, doing some cool, fun dates. It's a level or seriousness that [we] really haven't gotten to yet. And there's a lot at stake."
Zach teased "the most difficult decisions of all time" are coming up and the idea of watching it all back is "a little nerve-wracking."
"I'm getting butterflies thinking about going back to that time and looking at it, because it was a lot to take in... The nerves when you meet the families is a lot," Zach noted.
When asked if there was one woman in particular whose family he was extremely nervous to meet, for any reason, Zach replied, "It was Ariel's family."
Becca recalled Ariel's joke about how her father had confused The Bachelor with Game of Thrones and thought everyone was going to be naked on the show.
"I was a little nervous but excited to meet him, but I was also warned -- well, not warned, but prepared -- for her brother," Zach explained.
"I'm an older brother myself. I have sisters who have had boyfriends and I've played the macho, older-brother role at a younger time. But she prepared me for that, and so I was really nervous going into meeting her brother."
Without giving any spoilers away, Zach disclosed, "I don't know if [Ariel's brother] is a big fan of this whole show thing."
Becca pointed out how Zach also probably felt a lot of pressure because the women had presumably expected him to ask for their parents' blessing to potentially propose marriage at the end of the show.
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"Every hometown, you're prepared to have probably the toughest discussion you could ever have, because you're speaking with fathers, mothers, and siblings. For me, I personally believe that you do need to ask for that blessing," Zach explained.
"I want them to feel as comfortable as they can with me, but regardless, it's still their family and their daughter. I want them to feel comfortable or feel safe with me, so it was very difficult for a lot of the family to wrap their head around, and I completely understand."
Zach said he was "prepared for anything that could happen," positive or negative.
While Zach is admittedly "pretty nervous" to watch the hometowns episode Monday, March 13 at 8PM ET/PT on ABC, he said each date was very "special" and viewers will see how each family is "very unique."
"It was an overall great experience," Zach said. "But that doesn't take away from the fact it was maybe the hardest week -- maybe."
"Well, I know I felt like that was one of the most stressful weeks of this entire thing," he clarified, "because families are involved and I'm a big brother in my own life. I'm going to be meeting big brothers and I know exactly how they feel about me."
After hometowns, The Bachelor: The Women Tell All airs Tuesday, March 14 on ABC.
The Bachelor will then feature Fantasy Suites, Zach selecting his Final 2 bachelorettes, and the Final Rose Ceremony fans have been waiting for.
"I am excited for the end of it, for selfish reasons, to kind of start my life with someone," Zach teased, suggesting that he did find love and is currently in a relationship. "Tune in. But I'm excited for that phase of life."