Ghosting -- aka the Irish goodbye, the French exit -- refers to leaving a social gathering without saying your farewells. One moment you're at the bar, or the house party, or the Sunday morning wedding brunch. The next moment you're gone, in the manner of a ghost. (Source: Wordspy)

Ghosting，也叫爱尔兰式告别或法式告别，指没有跟任何人告别就离开某个社交活动的行为，即“不辞而别”。前一分钟，你还在酒吧、家庭聚会或周日早间的婚礼早午餐桌边，下一分钟你就不见了，像鬼魂一样无影无踪。

For example:

Where is Julie? Is she ghosting on us again?

朱莉去哪儿了？她又不辞而别了？