As much as I love Ygritte, and I do with my entire heart, she does not deal with anything emotional very well at all; as you can see with her shooting Jon for leaving her again. I put this down to her never having felt strongly for anybody at all in a romantic way - she lists other men she has bedded when she’s in the cave with Jon but she does not label them as boyfriends or people she was in love with, I almost question whether or not they were creations she made up to make Jon jealous.
In my opinion Jon was the first man she ever gave herself to, and when I say ‘gave herself’, I mean both physically and emotionally. When he left her she was left with all of these feelings she had absolutely no idea how to deal with - think back to when you were in your first relationship as a teenager, and then try to remember how distraught you were when that person left / moved on - nobody knew how to deal with that and that’s the problem with Ygritte; she is still young in respect to her feelings towards love.
When she finally realised Jon was leaving her for good for the likes of the rapers and murderers at Castle Black she was broken, but instead of mourning the relationship like a ‘normal’ person she dealt with it the only way she knew how - violence. In her psyche Ygritte believes that killing him / harming him will make her feel better and make all of the hurt go away but when it doesn’t, and she finds she doesn’t in fact want to hurt him, that hurts her more and dulls all of the instincts she has - ultimately leading to her death.
To sum up, Ygritte doesn’t know how to process her feelings in regards to love and heartbreak, and I love how raw she is with it. She’s almost primal with her behaviours toward emotions. Basically, break her heart and be prepared to be shot at. A lot.