Kourtney Kardashian and Scott Disick’s relationship may be in trouble in the wake of a recent paternity lawsuit filed by Michael Girgenti, the male model who claims to be the biological father of 3-year-old Mason.

Kardashian and Disick have been photographed during tense arguments ever since Girgenti filed court documents demanding joint custody of Mason, whom he claims to have fathered. While Kardashian maintains that Disick is, in fact, Mason’s real dad, the Lord is clearly unhappy with Girgenti’s bid for a court-ordered DNA test to determine the toddler’s biological father.

Kourtney Kardashian, Scott Disick and Mason Kourtney Kardashian and Scott Disick are putting on a united front, but they have been increasingly photographed in the middle of tense fights, likely about the identity of Mason's biological father.

Kardashian and Disick have attempted to present a united front, even going to an attorney together to deal with the paternity lawsuit. Yet the cracks in their relationship are beginning to show. The parents of Mason and Penelope were photographed on Monday night leaving chic eatery Sugarfish Sushi, but Kardashian and Disick were far from lovey-dovey. Disick looked frustrated and fed up with his girlfriend, fueling rumors that he may not believe Kardashian’s claims that Girgenti’s cheating story is "absurd."

Kardashian and Disick’s latest argument came days after it was revealed that Girgenti had sent a private letter to the reality star begging for a paternity test. “My attentions [sic] are not to hurt the family you’ve created with Scott. But at the same time, Mason deserves to know the truth,” Girgenti wrote on April 23. “I assure you I don’t take being a father lightly. I will be a great father to Mason,” Girgenti insisted.

Kourtney Kardashian, Scott Disick and Penelope Scott Disick appears to be keeping his distance from Kourtney Kardashian, after Michael Girgenti filed a paternity lawsuit demanding joint custody of 3-year-old Mason.

The male model, who Kardashian met at a steamy photo shoot in 2008, warned the Keeping Up With The Kardashians star that he would take the matter to court if his requests were not met. “Please take this final request for a DNA test seriously. Because if you don’t, I will be forced to take legal action and sue,” Girgenti said.

Kardashian has remained tight-lipped about the paternity scandal surrounding Mason, but her attorney was quick to slam Girgenti’s story as untrue. “This individual has been selling false and fabricated stories to the tabloids for years about Kourtney Kardashian and her son, Mason. Scott Disick is Mason’s father,” her lawyer, Todd Wilson, told E!. “His claims are absurd and this is simply another shameful attempt to gain publicity and profit form fictional stories about my client,” Kardashian’s attorney added.