Talk about a close call! Newly separated couple Justin Theroux and Jennifer Aniston almost came face-to-face with each other at Jimmy Kimmel's son's birthday party. A source exclusively told In Touch that the 46-year-old actor left after 40 minutes because he got wind that Jen — who seemed "nervous and skittish" at the bash — had just arrived. "They're trying to move on and are not really communicating," a source close to the duo said. "It would have been extremely uncomfortable."

Another insider told the Daily Mail, "It was obvious that he was alerted to [Jen's] arrival." Luckily, Justin was able to pose for a photo op with the birthday boy before making his sneaky exit.

He shared a few adorable pictures with Jimmy's son, Billy — who just turned one and has already undergone several heart surgeries for congenital heart disease — on social media. "Happy ONE year birthday Billy! A boy who in 365 days has done more for American national health care than we could all wish to do in our lifetimes," Justin wrote. "He doesn't even know yet how courageous he is. An honor to know him and his incredible and equally courageous parents. Thank you @CedarsSinai & @ChildrensLA #registertovote."

Jen and Justin have been longtime pals of Jimmy, his wife, Molly McNearney, and their family, so it's not a surprise that they were both invited. However, now that they have decided to end their marriage, running in the same circle of friends could prove diffcult since they are trying not to have any contact with each other.

The 49-year-old Friends alum announced the split in a joint message released by her publicist, Stephen Huvane, on Feb. 15, 2018. "In an effort to reduce any further speculation, we have decided to announce our separation. This decision was mutual and lovingly made at the end of last year," the statement explained. "We are two best friends who have decided to part ways as a couple, but look forward to continuing our cherished friendship."

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