I just don’t understand

I’m trying to tell myself that it’s okay to not understand and that I can move on without it, but it is just so so hard. We were together for nearly 7 years. Lived together for 5 years. We had a great relationship. There were some issues that we were working on, but I thought that we were working on it and progressing so well. We had so many great conversations where we listened to each other, understood each other, reassured each other and moved forward. What happened? How do we go from that to blindsiding me only days later? Literally in the days leading up to it she reassured me, she told me she loved me, she was giving me kisses before she left for work, what happened? Were those conversations just a lie and if so, why lie to me? You could have just been up front and honest and not string me along and get my hopes up. As I’ve been learning about attachment styles, I started to talk to her about it and she said on her own volition that she thinks she’s an avoidant. I think so too, but that doesn’t make me feel any better or understand any better. She is someone who has always struggled feeling her feelings and communicating them, but again that’s something else we were working on and I thought she was doing so well.