Well, you know that Lewis performed the surgery on Wilbur to keep the Timor Adducere from attacking. After Wilbur went in, Violet left and she was super overwhelmed and just left. I felt like that was something that bound to happen, so she's been gone. Wilbur had been in a coma for a while, after the surgery. In the final chapter, he wakes up in the hospital he had been transferred to. Since Violet had contacted Dash while she had been away, Dash calls her when Wilbur wakes up and has her go. The ending is them reuniting.