Depending on the which state and which insurance company, etc…
Your friend is considered a “permissive user” and may or may not be covered as a driver depending on what your policy allows. Permissive users do NOT live at your residence and are not regular users of the car.
If your policy will not pay because it does not allow for permissive use, her policy may cover her while driving a “non-owned car,” meaning a car not owned by her. If she carries Collision or Uninsured/Underinsured Motorist on her policy and her policy will extend to a non-owned car, you’ll be covered.
What your insurance company is doing is protecting itself by advising you in the beginning that there is a “coverage question” in your claim. It does not mean that they are denying the claim, only that they need to make sure they understand all the facts of the accident, confirm who is liable and that none of the policy conditions have been violated.
In my experience, if your car is not faulted in the accident, your collision coverage would apply regardless of who was driving (with the possible exception of an excluded driver). After all, if you car were unoccupied and then hit by an uninsured driver, your policy would pay up pronto if you had Collision or UIM.