As MarkRae says, it depends what you are trying to convey.
Do you mean the grief is hers alone, no-one but her feels the grief, or no-one feels it in the same way she does?
I only have eyes for you - I'm the only one who fancies you
I have only eyes for you - I can look but not touch
I have eyes only for you - You're the only one I fancy
Sally's grief was so intense, an intensity nobody else could feel or understand.
Only Sally felt the grief; others were oblivious to what she was feeling.