The 'Voice' mentor loves spending time with Rutler but admitted the footwear for hiking is not her usual choice, reported Contactmusic.
"My boyfriend and I started hiking. He got me in a pair of sneakers - no heels, no red soles. So out of character for me," said Aguilera.
The 31-year-old singer also revealed her son Max, four, - from her marriage to Jordan Bratman - doesn't mind when paparazzi follow them.
"Paparazzi followed me at my son's soccer game the other day. I was complaining but he said 'Don't worry Mama. They're not taking pictures of you, they're taking pictures of me'," she said.