wandamaximoffs:

When Wanda lost Pietro in The Avengers: Age of Ultron, she was ready to die and yet Vision saved her. In The Avengers: Infinity War, she breaks down while having to destroy the stone (thus killing Vision, the person she loves) and simultaneously holds back Thanos. 

When Thanos turns back time to get the stone, Wanda has to watch him die a second time after she had to do it itself. When death comes round a second time, she is relieved.