Often for Alice, seeing the future is more of a burden than a gift. Especially when she starts to have the most disturbing visions about Jasper, and the shock causes her to remember her cruel treatment in the asylum.
It only grows worse, of course, as she finds out Jasper, the man she loves above all else, is allied with the newborn army, and Victoria, and there is nothing she can do to stop the Volturi from doing their job and getting rid of him.