Have you considered depression? Often when the enormity of what has just happened hits home, instead of feeling elated, some patients actually spiral into depression. For us it was 6 weeks out but wasn't recognised for another 3 months.

the other suggestion I have is that she is possibly feeling smothered?

You are doing the right thing in not taking it personally - she cannot think about you right now and is not herself.

The only knock down drag out fights Alex and I ever had were during and just after treatment. I felt he was acting like an irresponsible 2 year old, and he thought I was an autocratic sergeant major. He also felt smothered, fussed over and resented me for it. We got past it (after many a night fantasising about dropping him off on the side of the road for some other poor woman to find), and we have the strongest relationship of any of our friends (IMO). He is considerate, regularly tells people that I am goddess (entirely true of course) and if he forgets, I tell them for him

It will get better, and that's a promise