Troian Bellisario is best known for playing an infamously smart snoop on ABC Family’s drama series “Pretty Little Liars,” but she might be spendingmore time investigating her personal life following a report of her fiancé's alleged cheating.

According to Star magazine, actor Patrick J. Adams, Bellisario’s love of three years, was allegedly caught stepping out on the 28-year-old TV star during a recent Canadian nightclub adventure. According to one eyewitness, Adams, 32,  of “Suits” and “Rosemary’s Baby” fame, was reportedly spotted “kissing” and “dirty dancing” with a mystery woman while visiting the hangout F-Stop in his hometown of Toronto on May 2.

“I arrived a little after 1 a.m. and there was a buzz in the nightclub that Patrick was there; he’s recently been in town filming the new season of ‘Suits,’” the eyewitness told the magazine, adding that the actor was accompanied by an “attractive blonde” and another couple at the hotspot.

While Adams has been officially engaged to Bellisario for three months, the insider is claiming that the TV star appeared to have no qualms about getting friendly with the mystery clubgoer. “They were sitting together in private booth, drinking and laughing. At one point, the blonde jumped up and sat in Patrick’s lap,” said the insider, adding that the actor reciprocated by placing his arm around the woman. “Occasionally, other people would come and try to talk with him, but it seemed clear to me that he basically wanted to be left alone,” said the eyewitness.

Following their private chat, the tabloid claims that Adams went on to dirty dance with the female before the duo engaged in PDA. “They were hugging and grinding on the dance floor,” said the source. “Then the blonde grabbed Patrick’s face and they kissed deeply.”

While the eyewitness is reporting that Adams didn’t leave with only the company of the female (he reportedly left the hotspot at around 2 a.m. with a total of three pals), the onlooker stated that his behavior wasn’t that of a newly engaged man. “For someone who’s supposed to be engaged, he didn’t really seem like he was trying to be inconspicuous with this woman,” said the insider.

Bellisario and Adams have yet to comment on the alleged cheating scandal.

The actors first met while co-starring in a play in 2009. The couple's engagement was revealed in February, a friend close to the couple telling Us Weekly that the pair secretly agreed to tie the knot in January. One February 26, one day following the nuptial buzz, Bellisario was spotted wearing a diamond sparkler on her ring finger while leaving the H&M show during Paris Fashion Week.

Season 5 of “Pretty Little Liars” premieres on ABC Family June 10 at 8 p.m. EDT. “Suits” kicks off the fourth season June 11 at 9 p.m. EDT on the USA Network. Part 2 of "Rosemary's Baby," starring Adams alongside Zoe Saldana, concludes May 15 at 9 p.m. EDT on NBC.