"We ask that everyone kindly respect Lea's privacy during this devastating time. Thank you," a rep for the 26-year-old actress told the media on Sunday.
Monteith and Michele's off-screen relationship went public in February of 2012, though the two had been "Glee" co-stars since 2009. Michele supported Monteith when he checked into rehab last April, saying in a statement: "I love and support Cory and will stand by him through this. I am grateful and proud he made this decision."
Several of Monteith and Michele's "Glee" co-stars have also taken to Twitter to express their condolences and grief, including Mark Salling, who tweeted then deleted a simple "no."