Miranda Lambert and Blake Shelton
thought she knew everything about her husband Blake Shelton
, until she watched him on The Voice
"We all know he's a ham on camera," she tells PEOPLE, "but I see this side of him that's softer, almost fatherly or big brotherly."
The country singers, who married in May of last year
, have been together since 2005. And Shelton, Lambert said, is the same off camera as he is on camera. But this "softer" side surprised her.
"It's hard to explain," she says. "He's so protective of his [Voice
team]. He has this side to him that I didn't know about."
And no wonder they make such beautiful music together: Sunday night, besides Shelton's co-hosting the ACM Awards
(with Reba McEntire), he also picked up the top male vocalist prize, while Lambert was a double winner – for top female vocalist and for album of the year, Four the Record