Ah, the dreaded moment when you run into your ex...and they're not alone.
That's right: they've moved on. They have a new boo. And that boo is not you.
The cast of "Girls" knows the feeling, with some of their characters getting firsthand experience of this little displeasure in the show's current season. Guest star Gillian Jacobs crashes into the tight-knit group of friends when she starts dating Adam (Adam Driver). Needless to say, Hannah (Lena Dunham) is not pleased.
"I am an unwelcome presence for Hannah," Jacobs told MTV News at the premiere for "Girls" season four. "She does not want me around. I am not her best friend."
So in the situation that you run into your ex and their new fling, what's one to do?
"The less said, the better, right?" Jacobs said. "To be very gracious. Keep your dignity intact. And maybe keep 90 percent of your thoughts to yourself."
"There's no way for it to not be awkward," Jemima Kirke, who plays Jessa, advised. "Always be sweet, never be catty."
Alex Karpovsky had different advice: GTFO.
"Scan the room for an exit sign," he said. "Bolt."