You never know what she is going through. After living outside for several years adjusting to another environment is different. Did you ever try Asking her what she is going through is something bothering her? You can assure her talking to you she might feel free and it’s a space. Mostly importantly saying all the things above you can give her some time.

I heard even from my office c
Friends as we work in the same company that she decided before going from here that she ll leave me once she go there and there are no reasons of it everything was good between us

Change is the only constant dear. Be calm and focus on something productive, you always wanted to do but couldn’t do. Like learn swimming, gyming, singing or start a good book. Anything which will make you better.

You made the best decision not everyone is meant to stay forever besides in life people come and go and those comings and leavings help us to grow.

It’s clearly mentioned that her love for you was not changeless so it’s better to focus on your career.