Cartwright had remained by Taylor's side throughout the season, even after he admitted to cheating on her with a former co-worker, which Cartwright said she had forgiven him for.
And her understanding was repaid when Taylor decided to end things with her, apparently without any warning.
"This has 150 million percent nothing to do with you. I need to make some changes. You deserve to be happy, you deserve to get married, you deserve to have kids, you deserve to have someone treat you like the princess that you are," Taylor told Cartwright. "I just am not that person."
The 38-year-old reality star's break-up cliché parade continued as he told Cartwright that he's "not good in relationships."
"You deserve a lot better than me. I just don’t think we can be together anymore," he continued. "I’m not happy with myself. I don’t like who I am, and it's not because of you. Look at all the s— I’ve caused this summer. Look at everything."
While no one could disagree with a single self-deprecating thing Taylor said, Cartwright was still devastated by the split, asking Taylor, "How can you do this to me when I’ve been through so much and I’m trying to help you and trying to work on things with you?"
"I wanted to make this work [but] I need to be alone. I need to be by myself," Taylor replied. "It's not you, it's me, and I need space."
After spewing profanities at Taylor and storming out of their apartment, Cartwright tearfully and angrily explained to the Vanderpump cameras how Taylor had "betrayed" her time and again.
"He's cheated on me, he's begged for me back, he's played mind games with me," she said in her confessional. "I know that he’s not changing and he's always going to be the same Jax Taylor he always has been."
Although it seems that Cartwright's rage -- and Taylor's need to be by himself to discover who he really is -- didn't last too long. Their breakup during this episode of Vanderpump Rules was filmed back in August, and the pair have apparently reconciled.
Cartwright has posted numerous romantic photos of herself and Taylor to Instagram in the months since the split. She posted the couple's most recent photo on April 11, writing, "New Summer, New Us," along with a double heart emoji.
ET caught up with Cartwright and Taylor at Daily Mail’s "Unwrap the Holidays" party in New York City back in December -- just after the episode revealing Taylor's previous infidelity aired but three months after the "breakup" fans watched on Monday -- and they opened up about their relationship.
“It's hard. Very, very, very hard … We took some time trying to work on things, but we're back together," Cartwright said. "[It’s] still working."
“Everybody goes through the same things that we do, some good, some bad," Jax added. “We're going through some things, working it out and, yeah, it's going good now. We're doing a lot better than we were."
Check out the video below to hear more from the couple about how they've weathered the storms in their relationship.
Vanderpump Rules airs Mondays at 9 p.m. ET/PT on Bravo.