Lol, I'm pretty sure it means netorare, and it's where the protagonist doesn't end up with their original partner; literally means taken away by having sex with someone else
But the black haired girl is named Yui in .925 and this one
Yeah, it's most likely the same Yui in both.
Where does it say her name is Yui in this story? The only thing I could find was the shot of the cell phone and the name was cut off in that. It could be Yuuko or Yukiko or something else that starts with "Yu".
Well if we're still on this topic, it's on the first page, bottom left panel that says "Yui-ch" on the cell phone screen