Saying that someone who committed suicide 'quit' or 'left' is the word game. Because as you express what's happened you're also assigning an interpretation to what it meant to that person, or a motive for why he did it. To say you've 'lost' someone is neutral because it doesn't speak to the other person at all, but only to what their suicide or death means to you personally (a subject you should be an expert at). I can see people choosing some 'quit' language when they have baggage over a suicide, like some resentment that a loved one has chosen that way -- and that's normal and part of grief. But I don't see it as the more honest answer.
