"It's definitely an emotional roller coaster for Katie. She doesn't hold back and will tell it like it is," the source explained.
"At one point, she threatened to quit the show. It really got to her and she couldn't take it anymore. She just walked away from cameras."
The 30-year-old bank marketing manager from Lynnwood, WA, will certainly have her hands full when she meets 30 bachelors, including one "mystery-box contestant," when The Bachelorette'snew season premieres Monday, June 7 at 8PM ET/PT on ABC.
"[Katie] kept changing how she felt and her thoughts were all over the place," the source said. "You will see later on this season how difficult it was for her."
The source added that Katie had to figure out which guys were really on the show to find love with her.
"Like every season, there's a villain -- guys who are on the show for the wrong reasons, guys who have a secret or some kind of scandal and surprises," the source told the magazine.
A The Bachelorette promo ABC released on May 26 showed Katie crying, storming away from cameras and shouting, "I'm done! Someone book my flight home!"
Katie was eliminated from Matt James' The Bachelor season before hometown dates, but she made a lasting impression on Matt and viewers with her raunchy humor. She also put an end to bullying in the house on Season 25 and took pride in being unapologetically herself.
"Tayshia and Kaitlyn stepped in multiple times to give [Katie] guidance and offer her advice," the source shared.
"They helped her with ruling out some guys but ultimately Katie went with her gut feeling and made decisions that were best for her."
Katie's entireThe Bachelorette season was taped at the Hyatt Regency Tamaya in Santa Ana Pueblo, New Mexico with quarantine and COVID-19 safety measures in place, according to Reality Steve spoiler blogger Steve Carbone.