I dont know what to do

I have this 4 year relationship with my girlfriend. Ive only been with her all thia time. We have an LDR relationship but we managed. On our second yr together she had anxiety and depression. Since then she suffered from that it has been quite difficult. I am still trying my best to understand her but its slowly draining me also. She keeps telling me that Ive changed but for me I really dont see how I changed. I keep asking her how I changed but she just tells me to reflect. So Im really confused how I changed. One thing I know that changed is I dont share my problems with her anymore because everytime I try she dismisses it or shes not interested in listening. I still do care about her and I know what shes going through is difficult thats why I understand why she acts like that but now I feel like our relationship is dragging me down and I feel somehow if I dont do something my career will be affected.