Who an earth are you to dictate somebody's grief?
It's a journey, one of the most horrid and gut wrenching. It's not to be rushed, it's not linear, it's up, down, hills, mountains, kerbs.
And yes. Maybe respectfully because of sons, and perhaps feels guilty for moving on.
By the way, divorce and death, they're very very different, and shouldn't be treated the same, at all.
She isn't your friend on Facebook? Boohoo. She hasn't added you. She doesn't actually need to change her photo or think about what she's writing in order not to irk you, so actually, it's nothing to do with you?
Please do some research about grieving.
*Yes there might be an element of she might not be fully ready - but if and when she is, sadly, not with you.