Arie was excited to take the girls on a grounded group date -- a big departure from luxury yachts and parasailing -- but the date turned out to be a bit of a disaster.
"I was truly shocked that the bowling date caused so much drama," Arie wrote in his People blog.
"Was [Krystal's reaction] a red flag for me personally? Yes, totally. I still, to this day, see the events very differently from her. The choice to not join the cocktail party was pretty immature and irrational."
When Arie brought a group of his bachelorettes bowling in Florida, they split up into two teams, and the winning team was supposed to receive extra time with Arie that night.
However, Arie decided last minute he would invite the losing team to the afterparty as well, and Krystal felt disrespected and offended -- so much so, that she decided not to come to the gathering and was accused of calling the Bachelor "a liar" off-camera.
"I thought the idea of a friendly competition for time at the cocktail party was fun, but after reflecting I decided that it would be nice to invite all of the women," Arie explained.
"At the end of the day, finding love and finding my future wife is one of the most important decisions of my entire life and maybe a bowling competition shouldn't dictate who I spend time with. It was an honest change of heart!"
He added, "There are a lot of qualities I want in my future wife, and believe it or not, winning at bowling is not at the top of that list."
Arie couldn't believe the date took such a drastic turn, with Krystal getting angry at him and questioning his character.
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"The fallout after the bowling date was one of the most disappointing and stressful parts of my time as the Bachelor," Arie admitted.
"Krystal's actions were confusing and misguided. There are two sides to every coin, though. For all the obvious disappointment I felt about Krystal, I felt equal parts pride and connection to the women who came to my defense."
Arie appreciated the fact that Bekah Martinez and Kendall Long had his back. The girls made it known that Krystal's behavior was unacceptable, mainly because she bad-mouthed Arie when it wasn't deserved.
"Bekah and Kendall really put themselves out there to defend me and my actions, and it says so much about their character that they were willing to speak out on behalf of me," Arie wrote.
Arie said he understands why Bachelor Nation has been questioning and, in many cases, criticizing his decision to keep Krystal around.
"[But] the thing about love is, it's not always easy. It's not all exotic dates and romantic one-on-ones and sunsets. She told me she was stressed and made a mistake and got angry. I've made mistakes and been upset about things I shouldn't have been upset about. We all do that, it's human," Arie explained.
"The connection Krystal and I had that first week in Scottsdale was real, and I wasn't ready to throw it away just because she was having a hard week. That didn't seem fair because we've all had irrational blow-ups before."
Watching the episode back, Arie was surprised to see several bachelorettes confront Krystal about her antics, but he was very proud of them.
"It was wild watching all the women confront Krystal," Arie said. "I am attracted to people who are strong and can stand up for themselves, and though I had no idea these confrontations were happening, I am proud of everyone for speaking their mind."