"She is in a totally different space than [she was] months ago," a source told E! News of Lambert. "She has no issues with Blake and is happy that he is in a good place in his life and also in love."
Shelton is smitten with girlfriend Gwen Stefani, but Lambert also reportedly has a "crazy connection" with East.
"Whenever they are together they act like two free spirits... Miranda adores Anderson," the source continued. "They understand each other. Anderson has given Miranda this confidence she hasn't felt in some time. They are very supportive with each other and their careers."
Another source added, "Anderson and Miranda are serious. They have met both sides of their families. Both their families love what they have. They seem like they are in such a great place. They spend so much time together. They are also very involved with Miranda's animals. That's a big part of her life and Anderson is a huge animal lover."
The formerNashville Star finalist and East made their red carpet debut together at the 2016 Academy of Country Music Awards in Las Vegas on Sunday.
East, a blues/pop musician, was reportedly "a little nervous" about the public appearance and cameras flashing but "so happy to be there by Miranda's side" at the same time. An eyewitness said they were very affectionate with one another and East seemed attentive.
Even a run-in with Shelton couldn't have ruined Lambert's good time. She was reportedly "not nervous at all" about potentially seeing the country star.
The "Little Red Wagon" singer "did not avoid him," a source told E! News. "She just did not go out of her way to bump into him. If they did, she would [have said] hi."
"Blake and Miranda were married, so they are not strangers," an insider elaborated. "Miranda will always have a certain love for Blake, but the romantic and forever feelings are gone."
Lambert won Female Vocalist of the Year for the sixth consecutive year at the ACM Awards. She also walked away with the award for Vocal Event of the Year with Little Big Town for their song "Smokin' and Drinkin.'"
Lambert finished third on the first season of Nashville Star. She also served as the adviser for "Team Shakira" on The Voice's sixth edition.