You’re not killing her, not really. Just bear with me for a minute. This is one of my crazy creative writing exercises.
First, write a short scene where a major character gets killed. Show it from the perspective of another viewpoint character. How it happens is up to you, but it should be directly connected to the main conflict of the story. No random bus accidents here.
If your characters are pursuing a killer, have the killer strike. If they’re climbing an unconquerable mountain, have one of your characters fall to his death. Make it really happen. Write it out.
Here’s the important part: have the point-of-view character react to the death. What do they feel? Shock? Disbelief? Anger? Guilt? Put it in there.
Got it? Good.
Now, go back and change the scene so that the character just barely survives. Or have your point-of-view character realize that she misread what she saw. Whatever you do, let the audience believe for just a moment that maybe the character really did die. Then pull them back from that ledge and let the character live on. But keep the emotion in there.
Now, for the follow up. How does this event change your characters later? Do they feel differently about each other after this brush with death? They should. At the least, they should realize what they really mean to one another. Ideally, they should realize something new about themselves.