Blake Shelton on the cover of PEOPLE
05/29/2013 AT 08:00 AM EDT
It's been two years since Miranda Lambert
and Blake Shelton tied the knot
, but it hasn't always been total bliss for the couple.
In recent months, the country stars have been the subject of rumors about troubles in their relationship. Now, Shelton is opening up about their marriage – and he tells PEOPLE that there are no secrets between the two.
"[I tell Miranda], 'I have nothing to hide from you,' " he says.
In fact, The Voice
judge says one secret to making their marriage work is giving Lambert access to his phone – if she wants it. "That's always been our policy: 'Here's my phone. Go through it,' " he says.
"That's really the kind of trust we have," Shelton continues. "There are no secrets. [I'll say,] 'Go dig through my drawers or my computer if you feel like you need to.' And that's been a really good thing, because I don't want her to ever have any doubts."
Even amid the rumors, Shelton and Lambert seem undaunted. Days before their May 14 anniversary, Shelton jetted to Bakersfield, Calif., for an unannounced performance at Lambert's Pistol Annies show. And the two will appear together Wednesday night for the televised benefit Healing in the Heartland
on NBC, which will raise money for victims of the tornado
in Shelton's homestate of Oklahoma.
For more on how Shelton and Lambert have kept their marriage strong, pick up a copy of this week's PEOPLE, on newsstands nationwide Friday