Rachel would never blame Becca -- who will be starring as The Bachelorette's upcoming Season 14 star -- for her failed engagement to Arie, but she apparently believes the Minnesota publicist got the ball rolling on Arie's reunion with his runner-up, Lauren Burnham.
"To be honest, the day Becca let Arie slide into Lauren's DMs opened Pandora's box," Rachel wrote in her Us Weekly blog.
Once he got engaged to Becca, Arie said he was open with his then-fiancee about how he still had feelings for Lauren, whom he had also fallen in love with on The Bachelor. (Becca says, however, she was not made aware of the full extent of his feelings).
Arie therefore asked Becca if he could contact Lauren to hopefully relieve some of his guilt for dumping her in Peru and maybe achieve some closure as well, and Becca obliged.
"Kudos to Becca for trying to allow Arie to get the closure she thought he needed. But girl, this was an engagement. The fact that this grown ass man wanted to contact the other girl he was in love with is a HUGE problem," Rachel wrote.
"That was the beginning of the end. Sometimes we want something so bad that we ignore the writing on the wall."
Prior to Arie texting and calling Lauren, Becca had also caught the 36-year-old pro racing driver liking her Instagram posts.
"In the end, I applaud Becca for being so gracious at After the Final Rose, but maybe she was just a little too polite," Rachel admitted. "It is okay to be angry and upset -- you were wronged and we would all understand that emotion."
Having starred on The Bachelorette's thirteenth season last year, Rachel said she understands how Arie's heart could be so conflicted, but she couldn't make sense of the fact he proposed marriage to Becca under those circumstances.
"As the lead, you have the power to say, 'No.' You have the power to say, 'I am not ready.' We have seen this before. Arie could have said no, and I think for Arie to make this 'safe' decision was selfish. He did not take into account the ramifications of his decision. He did not consider Becca or Lauren," Rachel insisted in her Us blog.
"He only considered himself. He seemed to be so conflicted that he might as well have flipped a coin on who to get engaged to; if it didn't work out with one, then let's go ahead and try the other one out. Oh wait, that's pretty much what he did."
Rachel believed that Arie's change of heart was pretty immediate.
"He admitted and was honest about having strong feelings for Lauren to Becca pretty soon into their engagement. His honesty did not make his actions any better or justify his indecisiveness," Rachel noted.
"And the fact that he kept reminding Becca of his openness infuriated me; it was almost as if he was saying to her, 'I told you this was a possibility.'"
Rachel also didn't appreciate how Arie continued dating and getting to know Becca while having Lauren in the back of his mind.
"He continued to plan a future with Becca while trying to build something with [Lauren]. He literally had one girl and kept the other in his pocket until he knew what to do for sure. He was having his cake and eating it too," Rachel claimed.
"He was testing the waters. He was searching for the certainty he did not have when proposing the first time. Wake up call, you can never be 100 percent certain."
Arie conducted numerous press interviews this week followingThe Bachelor finale, and he said he broke up with Becca on-camera so she could be the nextThe Bachelorette star and viewers would know the split was his doing and his fault.
"I think one, two, three and four are enough but Arie was full of too many excuses as to his actions. As they say, excuses are tools used by the incompetent to build monuments of nothingness," Rachel wrote.