It isn't fair or accurate to say Ah Chu was unloved. When she died, her lover Kiu Fung, her parents, and her younger sister Ah Chi all mourned her deeply. She'd only met Kiu Fung recently, however, and she literally had met her parents and sister only a day before she died.
But people who were more familiar with her were surprisingly unmoved by her passing. Mo Yung F'uk didn't mourn her, even though she'd served him loyally for years. Her counterpart Ah Bik, with whom she worked closely for a long time, seemingly did not miss her after they were separated. Ah Chu's close friend Wong Yu Yin also seemed strangely unmoved that Ah Chu was gone.
Not sure what Deun Yu's reaction was, and like Kiu Fung, Ah Chi, and Ah Chu's parents, Deun Yu hadn't known Ah Chu for very long. Curiously, of all the girls that (he thought for a time) were his sisters, Deun Yu never fell in love with Ah Chu or Ah Chi (mostly because those characters were being set up with Kiu Fung), and he didn't seem to mourn them as sisters either when they died.