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There may have been childhood abuse or a whole range of other stuff (guilt over which may have led the mother to take her own life).
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I hate this expression and you've forced me to say it: wow, just wow. What an outrageous and baseless speculation. No, I take the story as it's reported. Silly girl kills herself over a tiff with boyfriend. Loving supportive mother who gave everything for her daughter kills herself in grief.
Obviously there are cases where teenagers/young people kill themselves in response to abuse, for example:
http://news.bbc.co.uk/1/hi/england/london/6124190.stm
But the situation in OP is clearly nothing like that. And, yes, I do believe that in return for the financial and emotional investment parents make in their children in a normal, happy family, the children have obligations in return. No, I don't believe you have to marry someone unsuitable because your parents like them, or become a doctor when really you want to be an artist, or not take any risks or do anything differently from how your parents would.
But I believe that by fulfilling your obligation to yourself to live well, to find whatever your idea is of happiness and obtain for yourself on your own terms the best life possible given the start your parents have given you, you are also implicitly fulfilling your obligation to your parents. You are making the most of the life they have given you, and allowing them to find happiness in your happiness, and pride at your success. To kill yourself, when you have had loving, supportive parents, and you are not even someone with depressive or psychiatric issues, strikes me as a wicked, wicked thing to do. You are murdering your parents as well as yourself.