You're probably upset about the suicide and the box represents your feelings for this person and your unconscious is reminding you not to open that box, hence worrying about something that can't be changed.
I know the question has already been resolved but I wonder why your friend or anyone else, would give you a gift and then tell you not to open it ?
The box was you containg your memories of him, and it was purple for love, you loved him most now than before and the bow was the one that shot an arrow through his chest depressing him and killing him and you know the shooter. Don't you?
look some unresolved questions put unresolved and go ahead is good.
I think it represents the feelings of shame and pain that she kept inside, which she never told you. Purple and black is an unpleasant color combination, also the color of bad bruises.
In your dream, did you long to open the box, or did you dread it? What were your feelings?
It feels to me (but feeling is not knowing) that your friend's suicide left you with a mixture of negative feelings, like incomprehension and guilt, which feel as if they will never be resolved. That's what is in the box...
maybe she says don't go where she's been.. not to end like she did.. purple is the colour of good judgement and spiritual fulfilment.. and dreaming about a box is "To see a box in your dream signifies your instinctual nature and destructive impulses. Alternatively, you may be trying to preserve and protect some aspect of yourself. The box may also symbolize your limitations and restrictions. Consider the pun of "being boxed in".
To dream that you are opening a box indicates an aspect of yourself that was once hidden is now being revealed. It symbolizes self discovery. Consider your feelings as you open the box. If opening the box fills you will fear, you may be uncovering aspects of yourself that cause you to feel anxious. " http://www.dreammoods.com/dreamdictionary/b4.htm
Find your own meaning.. and interpretation :)
perhaps she wanted to talk about something, such as depression, but was unable to do so.