The story
He gave away her ticket and kissed someone else outside.
Samantha Hughes waited a year for the band's farewell concert, and Logan hands her seat to Sierra and does not think twice. He keeps choosing Sierra, drags out Sam's family trauma in public, and then leaves her behind during a fire. That is where the boy she loved stops existing. She withdraws from Berkeley, moves to New York, rebuilds with her mother and turns down every attempt to pull her back, including the begging.