Lying and cheating are obvious relationship dealbreakers.

But finding out that your partner confided in ChatGPT about relationship doubts? The romantic metrics are murkier.

For Lindsey Hall, a public relations professional who pens a Substack titled “Lindsey Hall Writes” — and wrote the recent essay “I Stumbled Upon My Boyfriend’s ChatGPT and It Ended Our Relationship” — this question came up when she accidentally came across her now ex-boyfriend’s ChatGPT history.

She recalled borrowing his laptop — as he sat beside her on his couch, sleeping — in order to respond to a client after her phone had died. On it, she found a modern-day girlfriend’s nightmare — a ChatGPT chat titled “Relationship Issues and Uncertainty.”

In the post, Hall recalled that she “stared at the words,” instantly wishing she had “never read what I did.”

“Now, here is where I am certain many will piously tell me I dug my own grave,” Hall wrote. “I invaded his privacy. That I never should’ve read what I read. That the man is allowed to share private thoughts with a robot he never intended for me to see.

“And of course all that is true,” she continued. “But I dare you to come across your partner’s ChatGPT, read those words, and not unravel all moral senses.”

When contacted by The Post, Hall admitted that “some” criticism of her actions “is fair” and that she “did invade his privacy, and I’ve never tried to pretend otherwise.”

While Hall wrote that she’d initially bristled — assuming that the focus would be on the chaos of her three cats, about which her ex had never been a huge fan — she froze when her eyes quickly landed on the final line of the AI bot’s analysis: “From what you’re sharing, you should consider ending the relationship.”

In the thread, Hall’s boyfriend had posed a series of concerns to his robot (named Freud), kicking off with the question, “Should I be in love after 3.5 months?” He followed with doubts about Hall’s lifestyle, sensitive nature, eating disorder history, and online writing, with the trio of cats eventually making their own appearance in the chat.

But to Hall, the kicker was his phrase, “And then there’s the whole attraction thing.”

“Look, it’s not that I think I’m a dime — I’m a realistic lady — but this man’s entire love language was rooted in physical affection,” Hall wrote. “It was quite literally the only type of love I felt certain from him … I reread it over and over because I genuinely could not make my brain process.”

But what “floored” Hall the most was that next to all the cons, there was no “pro” list.

“In the privacy of his own thoughts, I was not being held in the warm and forgiving light I had imagined …Then I read the line that I think I will probably remember to my grave: ‘I’m just not proud of her.’”

In the post, which to date has over 22,000 “likes” and topped 2,000 comments, Hall admitted that after uncovering that first AI conversation thread, she found — and read — “handfuls” more. Still shell-shocked, she slid out from underneath his embrace on the couch, gathered her things, and left as he remained there, snoozing.

As Hall explained to The Post, “What hurt wasn’t that he had private thoughts … everyone does. It was seeing them laid out so clinically, almost like our relationship had been turned into a performance review by AI. And none of it was favorable. There was no balancing of the scales, so to speak. And I simply could not be with someone that in the chambers of their thoughts did not have one positive attribute to share when evaluating the relationship.”

Following the incident, after a frantic barrage of texts from her ex asking what had happened — leading to his arrival at her house a half-hour later — she spit out her discovery: “‘I read everything … I read your whole f–king ChatGPT.’”

Hall recalled that her “stricken” boyfriend, whom she clarifies to her readers was “a strong man, a brilliant one too,” looked “horrified” and “instantly ashamed.”

While the pair attempted to talk out the debacle — which involved countless tears and apologies from the boyfriend, with frantic explanations that his confiding in AI was due to relationship anxiety and that he was still attracted to her — the damage was done.

While Hall and her partner continued dating for a few months afterward, the relationship eventually ended.

Now that an unspecified amount of time has passed, she reflected on the incident — even sharing that she does “forgive” him.

She hopes — but does not necessarily expect — that her readers will give her the same grace in return for the invasion of privacy.

“I also think the story struck a nerve because a lot of people recognized themselves in it, whether they identified with me, with him, or with the growing tendency to process human emotions through technology instead of uncomfortable or vulnerable conversations,” she told The Post. “At the end of the day, I didn’t share the story to villainize him. I went to great lengths to highlight his qualities I liked in the essay. I shared it because it did genuinely change how I think about intimacy, privacy and the role AI is starting to play in relationships.”

Hall — who noted in her post that “what made it so painful was how ordinary it was” — also saw a particular “irony” about the scenario.

“People say I violated privacy by reading it,” she told The Post, “but the relationship was already being emotionally outsourced to a machine that collects our data, anyhow.”