Amanda Stanton on How Lauren Bushnell's Engagement to Chris Lane Is Different From Ben Higgins (Exclusive)

Amanda Stanton knows her 'Bachelor' bestie well.

Amanda Stanton couldn't be more excited or her Bachelor bestie, Lauren Bushnell, following her engagement to singer Chris Lane. 

"I'm so happy for her. She's so happy," Stanton told ET's Lauren Zima on Thursday. "Selfishly I'm sad, because [she moved across the country, so] I miss her, but I'm also really happy for her.

Bushnell announced her engagement to Lane in June, after less than a year of dating. They're now living together in Nashville (in a new home), and just adopted a dog. The blonde beauty's happy news came two years after her split from Bachelor Ben Higgins. The pair split in May 2017, after a year and a half together. Since their breakup, Higgins has said he's realized they didn't have the most solid relationship, while Bushnell revealed she never gave Higgins her "whole heart."

Stanton said she notices the differences in Bushnell's relationship with Lane. "They're very compatible. They're super goofy together," she revealed. "She can fully be herself." 

"I adore Ben... [but] sometimes you're just not compatible. You know, you can be two great people, and it just doesn't work out," Stanton continued. "She's definitely very happy with Chris, and I love them together."

The mom of two thinks Bushnell and Lane will tie the knot "fairly soon," and she's excited about possibly being part of the big day. "I hope so," she shared. 

For now, Stanton is focused on her new book, Now Accepting Roses: Finding Myself While Searching for the One... and Other Lessons I Learned from The Bachelor.

"It's not so much about tips about finding a guy, it's more tips about being content with yourself and everything I've learned throughout my relationships and how to be independent," she teased. 

Now Accepting Roses is available where books are sold on Sept. 3.