Krystal became "a smitten kitten" with Arie on their first one-on-one date in his hometown of Scottsdale, AZ, which resulted in her being protective and possessive of him.
Krystal has been shown calling her competition "juvenile" and "obnoxious," while they in turn view her as "condescending," "fake" and "two-faced."
"It's already unusual to date multiple women at once, so it's not totally crazy to think there will be disagreements and have certain women just not get along," Arie wrote in his People blog.
"I knew since our one-on-one it was hard for Krystal to be back on group dates. I could sense tension between her and [Caroline Lunny] and [Tia Booth] but really didn't feel like it would be appropriate for me to involve myself in."
Arie, however, has learned quite a bit about Krystal's dynamic with the other women from watching The Bachelor episodes unfold on TV.
"Watching it back, I see so much more than I did in person, and it's hard to say now if I'd have done anything differently," Arie admitted.
"It isn't easy seeing these amazing women struggle with one another, but knowing what I know now -- I'm happy that I was patient to make sure I was making the right choices. Things don't always play out the way you expect, and I think next week you'll understand a little more."
Previews for next week's episode show Krystal getting into another heated argument with her competition.
Although Arie eliminated Caroline during the most recent Rose Ceremony, Tia is still around, and the two women are definitely at odds. Bekah Martinez will also apparently voice her issues with Krystal.
"Krystal has become a little unhinged," one bachelorette can be heard saying in the preview that aired after Monday night's episode, before Krystal complains to her cast members, "I don't want to be here."
Jenna Cooper is then shown warning Arie that Krystal had called him a liar "multiple times," and Arie was upset that the fitness coach had called his character "into question."
In the latest episode, Arie canceled the cocktail party because he felt confident in his elimination decisions.
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But before the 36-year-old pro racing driver turned real estate agent could hand out his first rose, Krystal asked to speak with him and reminded him that she was on the show for him and really cared for him.
"This week must have really rattled Krystal's confidence for her to pull me before the Rose Ceremony," Arie wrote in his blog.
"I wish I could say that we find our rhythm again next week, but our rocky pattern continues in a pretty shocking way," he teased. "Next week reveals new truths, tensions and love... I can't wait to share it with you guys."