Will a third time down the aisle be the charm for Reba McEntire? Though the singer has been divorced twice, she revealed she would definitely accept a proposal from boyfriend Rex Linn if he ever gets down on knee. “I’m truly committed to Rex. So if that’s something he feels totally strong about, that’s fine with me,” the country superstar, 69, told a reporter when asked about potentially tying the knot one day with Linn, 67. “He’s never been married before. So if he wants to experience that, I’m OK with that.” Though the pair first met in 1991, things stayed platonic until 2020, when McEntire …