What is the theme for Good girls are bad news
If its the title by Subhatra Sen Gupta then look for evidence of a 'change' theme. Go through all the story lines and pick out any special moments where a decision or change of some sort is imminent. This might be a pivotal moment where a character has to make a lfe changing decision or a point in a story where it changes direction to take the character along another path. Think about Robert Frost's poem 'Road Not Taken' and wonder about other likely scenarios and outcomes. Or go back and look at a character's past. Has she taken a different route, made different decisions from others. How did that affect her future life, friends, family?
Also take the storylines character by character, pinpointing places where early decisions or life choices changed the character's personality for ever. What were the stimuli, causes or triggers for that and how are they coping? Look at Joyce's story 'Araby' for inspiration and comparison. His character is a boy who undergoes a 'right of passage' into a new realisation on an evening trip to a market, so adolescence might be a good area to look at as this is always a time of great upheaval, body changes, mood swings and family strain. Do the characters accept change, resist it or initiate it themselves and what are the consequences?
Look at culture too, because that obviously changes over the years. Has it been traumatic for the characters to adapt? Look for dialogue or thoughts to display this, and use them as quotes. All in all I think you will have plenty of material there for a good analytical piece if you work with depth and detail ! Good Luck!