(He wouldn't have known who Zhar or Yui was. Plus it was dark, and as I said there was barely any light since there was almost no moonlight)
(He's a spy trained by Lucas placed to watch yui yui has a heart felt moment with random dude notice is taken)
(I have an idea....) Lucy notices the spy and follows him. Before he even got near the castle she took him out by slitting his throat.
(Yui doesnt have any heart felt moment with any dude because shes madly in love with her finace Zhar)
Lucas smiles seeing Lucy off in the distance. "It's but a chess game little sister you killed a pawn but exposed your queen." (Remember he's way up high on a balcony looking out at this)
(Their conversation could not have been overheard. As well, Zhar never kissed her otr anything that night.)
(My point is multiple spy's on her for maybe being a part of the shadow she has a talk with a dude middle of the night some ones gonna follow dude)
(It's weird wen try keep talking and he puts his had on her shoulder to look her in the eyes and when she looks devistated when she has to leave plus if they reported to Lucas and were like she talked to this dude at this time and they didn't have any info on dude he would execute them)