Specific nightmare interpretation, involving death?

I think this dream has to do with your girlfriend leaving. You literally feel that your "heart is leaving" your body because your love is leaving you. You are trying to be strong and pretend that it's not upsetting to you that she is leaving but your older sister (a protective figure) calls you out and tells you that she can tell you're really upset and that it's "killing you inside" that you won't be able to be with her. When she mentions this you suddenly realized this was true and that's when you woke up...because you realized what you needed to. Hope this helps! :)