It does seem like things have changed. There is no way to know why this is unless she tells you. The end of social relationships can increase one's social anxiety. The uncertainty is very unsettling. Until you find out why things have changed yo don't really know what can be done.
First you need to accept that things of have changed. If your expectations are that things have not changed or they will eventually return to the way things were before may set you up for failure. Instead adopt the mentality that this friendship has changed but you still have the benefit of the friendship; it hasn't ended. Also keep in mind that the reason it has changed may have nothing to do with you. She could be going through something where she wants to isolate or she may not need a close friendship. You have to accept that the friendship has changed.
Reinvent the friendship to fit around those boundaries. It is better to have a new friendship than none. Then you won't lose this friendship because you can accept it in its new terms. This will salvage what is left of the friendship and reinvent it. Then you don't have to lose it but you have to think of it differently.
You can employ her in this process by being honest. Ask her what she can do in terms of what she needs and what she doesn't need. She may be willing to work on this together
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