Can anyone give /facepalm again? 
If Sheryl ever looks at Ranka then she's a selfish bitch bursting with jealousy and insecurity.
If Sheryl never looks at Ranka then she's a selfish bitch who cares only for herself...
None of those is the case
So you think Sheryl would give someone who she didn't even consider as a person advices and supports? Sheryl respected and saw potential in Ranka's voice. It is the contrary, Ranka's the one who never looks past her idol admiration and insecurity to actually care for Sheryl as a person.