As stars, Kim Kardashian and Kanye West's marriage has always been the subject of speculation and conjecture, but one thing is certain: Rumors of a troubled relationship between the two have popped up over the years.

Most recently, reports have surfaced that Kardashian, 39, is "furious" at her 43-year-old rapper husband after he claimed that the pair considered terminating Kardashian's first pregnancy, which eventually resulted in their daughter North.

"Kim is shocked that Kanye spoke about North at the rally," an insider told People magazine on Monday of West's remarks during his first campaign rally in South Carolina over the weekend. The couple also shares three other children -- sons Saint, 4, and Psalm, 1, and daughter Chicago, 2 -- together.

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"She is furious that he shared something so private," the source added.

A second source also told the outlet that "things have broken down significantly between the two of them, and it’s happened pretty suddenly."

A rep for Kardashian did not immediately respond to Fox News' request for comment.

On Sunday, West, speaking without a microphone, became tearful while talking about abortion, about his mother, who died following plastic surgery complications in 2007, and about his wife. "Even if my wife wants to divorce me after this speech, she brought North into the world even when I didn’t want to. She stood up and she protected that child. You know who else protected a child? Forty-three years ago, who do you think protected a child?” West said crying.

"My mom saved my life. My dad wanted to abort me. My mom saved my life, there would have been no Kanye West because my dad was too busy," he said.

West and Kardashian began dating in 2012, welcomed their first child, North, and became engaged in 2013 and married in 2014.

Reported issues between the couple date back several years, notably in 2016, when West and fellow rapper Wiz Khalifa dove into a Twitter feud, which resulted in West taking a jab at Khalifa's young son, whom he shares with Amber Rose, West's ex.

At the time, a source told People magazine that the two find themselves at odds over Twitter.

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"What causes friction in the marriage ... is Kanye’s compulsive tweeting," a source told People. "Kim can’t stand it. She is all for self-promotion, but doesn’t approve of Twitter drama.”

An insider also told Page Six that the pair argued "a lot" after Kardashian was robbed during Paris Fashion Week in 2016.

"Kim has completely calmed down her life, but Kanye is stubbornly refusing to let fear get in the way of what he wants to do," claimed the source.

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Similarly, a source told People that Kim's recovery from the robbery and Kanye's tour were "very trying for them both and not a good recipe for a happy marriage."

The "Gold Digger" rapper also reportedly lived apart from his wife and kids after being hospitalized in the same year.

“Kim is being very protective and doesn’t want Kanye around the kids right now,” a source told Us Weekly at the time. Although, per the outlet, an insider close to West denied the report.

The trouble seemed to continue, as another source told People magazine that Kardashian seemed "miserable" after West didn't slow down following his hospitalization.

“Kim still denies they are getting a divorce, but things are definitely not great between her and Kanye,” the source told the outlet, adding: “Kanye is supposed to rest and focus on his mental health. Instead, he has had a very busy week and is done resting.”

“Kim acts annoyed. She also seems miserable and is spending a lot of time with her family," the insider claimed.

Kim Kardashian and Kanye West (Photo by Karwai Tang/Getty Images)

Kim Kardashian and Kanye West (Photo by Karwai Tang/Getty Images)

More recently, the pair have been struggling amid the coronavirus quarantine.

“Kim and Kanye have been arguing a lot during the quarantine,” a source claimed to Us Weekly in April. “Kanye is really getting on Kim’s nerves.”

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According to the insider at the time, West had been "focused on creating," which caused Kardashian to feel like “all the parenting duties are falling on her.”

“Kim finds it frustrating that [Kanye] doesn’t ask her how he can help with the kids,” the source claimed to the outlet.

Fox News' Frank Miles contributed to this report