Per TMZ Sports, Kardashian broke up with Thompson after he allegedly cheated on her with one of her sister's friends at a party over the weekend.
"They aren't speaking," an unnamed source told Emily Marcus of US Weekly about the couple.
TMZ previously obtained surveillance footage from October 2017 showing Thompson kissing one woman at a hookah lounge in Washington D.C. Kardashian was three months pregnant with the couple's first child at the time.
Per Maria Pasquini of People, the couple reportedly were trying to repair their relationship after reconciling following Thompson's infidelity.
Kardashian and Thompson began dating in 2016. She gave birth to their daughter, True Thompson, last April.