The 26 year old played high school cheerleader Santana Lopez during the programme's first three seasons, but she recently graduated and moved to New York City to live with Lea Michele's Rachel Berry and Chris Colfer's Kurt Hummel.
The remainder of Rivera's castmates are finishing out their final years at William MCKinley High School, where they shoot on another set, and the actress admits the change has been difficult.
She tells New York Magazine, "It does feel like a different show and sometimes I get really sad about it. We shoot on the same sound stage, but there's this big door that separates the two worlds, so on my lunch breaks I'll go over there and see (MCHale) and (Ushkowitz) and everybody I haven't seen, like, 'I miss you guys! What are you doing?' I have no idea what they're doing! I have no idea about the gossip and drama with the new kids!"
And Rivera, who is currently recording a solo album, reveals she's still uncertain about whether she'll be returning for Glee's season five, adding, "You never really know what they (the writers) plan on doing... (I've) been on the show a really long time; I wasn't really sure what they were going to do with Santana, but I think that her story line is evolving and there is more to tell.
"I'd absolutely be down to be around for some portion of that. But there is the album stuff that I desperately want to get done."