Mark and Lexie just couldn't seem to get things right. While on this break, Mark had a one-night stand with Callie, resulting in her pregnancy. Lexie tried to reconcile with Mark, but her plans were quashed when she was informed of the bun-in-the-oven. That was when Jackson Avery entered the picture. Jackson had been interested in Lexie and consented to be a middle-man between her and Mark. After Mark and Lexie's relationship went south, Jackson was there to pick up the pieces. Lexie and Jackson dated for some time, but it was clear that Lexie still had feelings for Mark. This became apparent to Jackson at an inter-hospital softball game. Lexie beaned Mark's new girlfriend. An argument between Jackson and Lexie ensued and the two of them broke up.

Not knowing what to do next, Lexie sought the advice of Derek. Based on his advice, Lexie told Mark she still loved him. Mark didn't know how to respond and instead acted awkwardly around her. Lexie's time ended with the plane crash. She was trapped under debris from the crash and was quickly dying. There was nothing anyone can do to save her. Her last moments in this world were of Mark holding her hand and saying he loved her. RIP Lexie Grey.