Why Alice and Jasper Left?

After she "sees" the Volturi army approaching, she disappears with Jasper, leaving everyone to believe that they deserted the Cullens to save their own lives.

What happened to Alice and Jasper?

In New Moon, Jasper has graduated, leaving Alice and Edward to their final year in high school. At Bella's birthday party, Jasper loses control of his blood thirst when she gets a paper cut. Because of this incident, Edward decides to leave Bella behind while his family moves on to keep her safe.

Why did Jasper and Alice leave in Breaking Dawn Part 2?

Alice, who has the ability to get visions into the future, figures out that the Volturi will come after the Cullens. ... The vision makes her feel distressed. By the next day, Jasper and Alice are gone.