"The last time I saw Heather," an insider told Closer magazine, "she look like she was back on top."
Sources close to the Dynasty beauty -- who's fought substance abuse in her past -- praise Mani, 44, as "the right guy for Heather" and "a very stabilizing influence on her" since they first connected in May.
"Heather's priorities have shifted," the source said, adding that the top-rated plastic surgeon "came into her life at the perfect time.
"She's in a wonderful place -- and it shows."
At their daughter Ava's Sweet 16 party in Los Angeles Oct. 4, Locklear, 52, and Sambora, 54, were the proud parents, "hugging, kissing and fussing over Ava.
"They were making sure she was having fun," the source said.
All in all, Mani's "good for her," the insider said, adding that one of the doctor's best attributes in this relationship is his disconnection from show business.
He's not "from the Hollywood scene, so he doesn't have all the baggage that comes with that."