As the rest of the cast mourns Monteith's sudden death at age 31, Michele's grief is twofold -- she loses a castmate and off-screen boyfriend. Her grief will become public, too, as she acts out losing him onscreen in the next season of "Glee," where writers will have to determine how to handle his absence. Their characters have been dating on-and-off throughout the show.
"I don't even remember a time when he wasn't my boyfriend," Michele, 26, said in January. "No one knows me better than Cory."
With Michele's support, Monteith had checked himself into rehab in April and seemed to be doing better before he was found dead in his hotel room Saturday.
He had previously undergone rehab for "anything and everything" when he was 19 for struggles with addiction that started at age 13.
The couple had not yet talked engagement, but Monteith was planning to move into Michele's home in Los Angeles. Their relationship was going well before he died, despite some speculation to the contrary.
"They were 100 percent happy and together and in love at the time of his death," a source said. "They never broke up."
Michele has not released a statement about his death, but her representative requested privacy during the coming weeks.
Monteith's autopsy and toxicology results are expected to be completed today, and has been fast-tracked in Vancouver after the publicity his death has received.
Toxicology results, which normally take six weeks, are being made available in "2 or 3 days."
2014: The Year in Music [PHOTOS]