Keith Urban… where is Nicole Kidman?! The Australian-born country singer stepped out solo to the CMT Music Awards in Austin, Texas, on Sunday night, April 7, with his wife noticeably not in attendance, as he posed alone on the red carpet. Urban seemed in good spirits — despite missing his lovely lady by his side. The “Blue Ain’t Your Color” singer donned a plaid button-up shirt and black pants while holding up the peace sign, smiling and laughing for the flashing cameras. Urban isn’t nominated for this year’s awards show, however, he is set to perform at the Moody Center during the star-stud…