Psychologically speaking, sometimes when individuals are experiencing a disturbed mental/emotional state they will lash out and say things that they don't truly (deep down) believe and feel... I guess an appropriate analogy would be instances of toddlers having temper tantrums and telling their parents that they don't love them or that they 'hate' them... I'm not likening your girlfriend to a toddler here (lol), but just illustrating a point. It's possible that your girlfriend in that moment/instance acted in a manner that is not in alignment with her true feelings. It's also possible that she felt hurt (right or wrong and for whatever reason) and unconsciously reacted in a manner that would serve to 'get back you' in some regard. Maybe should even could have direct misplaced anger/frustration at you but which is really rooted in other areas of her life that you are not responsible for.

I don't know your girlfriend personally so I cannot say she is experiencing... That being said, you should find a means to speak with her about this so you can become more aware of what she truly thinks & feels regarding this sensitive subject matter. A single text message comment is simply not enough for you to utilize as evidence of her longterm or ongoing mindset & feelings...