The surprising pair ate at Estiatorio Milos in New York City, the restaurant confirmed to PEOPLE.
A source tells PEOPLE that Kardashian West, 38, was having dinner at the Midtown Manhattan restaurant while being filmed for Keeping Up with the Kardashians when Thompson, 28, arrived.
“Kim at dinner is boring, but Tristan ‘showing’ up makes things more interesting. It wasn’t a coincidence that Tristan showed up,” the source says.
Kim wore an elegant black ensemble, while the former NBA player opted for black pants and a black hoodie for the night out.
“Kim is the one who is really upset about this,” a source told PEOPLE after the cheating scandal. “She’s livid. She’s so angry, and she’s 100 percent on Khloé’s side. She’s there for Khloé, letting her vent and talk about it. They’ve been in constant contact, and Kim is totally supportive. Guys may come and go, but the bond between the girls is never going away, and they’re committed to supporting each other.”
Kardashian West unfollowed Thompson and Woods on Instagram after news of their hookup first broke.
“Kim is putting the blame squarely where it belongs, on Tristan,” the source said. “She is telling Khloé to move on and to focus on being the best mother she can be to True. But Kim isn’t going to talk about this much publicly. This isn’t her battle to fight in the public eye. But behind the scenes, she’s definitely making her opinion known.”
During the season 17 premiere of KUWTK on Sunday, Khloé was fearful of how Kim would react to Thompson showing up to their daughter True’s 1st birthday party.
“This situation, it’s a little awkward,” Khloé said in the episode. “Everyone is staring at us and I’m really concerned, a little uncomfortable, about Kim and Tristan’s dynamic.”
Thompson ended up getting into a confrontation with Kanye West at the party. Footage was shown of the two having an animated conversation, and while there was no audio, West later explained that Thompson was upset about the fact that the family used the intro to West’s song “Runaway” in a KUWTK teaser. (The lyrics reference toasting to “a—holes” and “scumbags.”)
Keeping Up with the Kardashians airs Sundays (9 p.m. ET) on E!