Khloe Kardashian and Tristan Thompson Get Cozy at Birthday Party

Khloe Kardashian and Tristan Thompson are attached at the hip again, but only for a moment. At least for now.

We've known the exes have been spending time together while co-parenting True over the past several weeks -- but at a friend's birthday party they looked very cozy again ... with no kid in sight.

In the vid, posted by Tristan's old teammate, Jordan Clarkson ... Khloe and Tristan are standing right next to each other while singing and holding up their phones. Notably, it looks like his arm is around her.

It's not as earth-shattering as those pregnancy rumors -- which were false -- but for these 2, any news is big news. Our sources say the party was going down at Tristan's home in L.A., but despite appearances, they're not back on as a couple.

We're told Tristan sees Khloe and their daughter every day ... and the pandemic has simply given them a chance to hang out more and work on their friendship.

Our sources say they still live separately, though, and insist there's no change to their relationship status ... still just friends and co-parents.

They are together on one thing, though -- we broke the story, Khloe and Tristan threatened to sue a woman for lying and defamation after she made claims he was the father of her child. Their lawyers say that's been proven false, and Tristan did eventually sue her.