Jason Mraz is engaged! The “I’m Yours” singer/songwriter, 33, is set to wed fellow musician Tristan Prettyman, his rep confirms to UsMagazine.com. “SHE SAID YES,” Mraz Tweeted late Thursday. His bride-to-be Prettyman, 28, added: “For Once. I Am Speechless…..i did good! holy crap! man of my dreams!!! for the rest of my life!!!”