Pretty sure this novel needs Tragedy and Betrayal tag.
YEA, AS IF!
The reason why FL is apathetic was because her trust and affection was betrayed by ML#1 who spoiled her in the past, only for her knowing later that ML#1 only regards her as his toy, even gone as far as to strangled her to near death because FL saw ML#1's murdered someone.
In despair, FL gave up and laughed in vanity knowing all of her life so far was built upon lies. The ML#1 thought she was amusing and decided to spare her life.
Ah, yeah. Almost forgot; her loyal attendant that was depicted as her silly friend yet cares a lot about her is actually a spy sent by ML#1 to monitor her 24/7.