Jason Mraz: 23 Reasons Why I Love Fiancee Tristan Prettyman

 Jason LaVeris/FilmMagic

How did Jason Mraz know that new fiancee Tristan Prettyman, 28, was The One? It was in the stars.

The "I'm Yours" singer, 33, explained on his blog Tuesday that their romance is linked by the number 23. It's their shared birthday (his is in June; hers in May) a shared tattoo and the day they met at a pal's birthday.

"We hit it off instantly by syncing our interest in this magical prime number," Mraz wrote. "Whenever she or I come upon it, whether being sat at table 23, or assigned seat 23 on a plane, we almost-always and/or involuntarily think about the other."

But despite their shared mysticism, the betrothal didn't go off without a hitch. One day before his planned December 23 seaside proposal, Mraz was still waiting for the ring to arrive via FedEx.

"I hung out in the driveway ALL DAY," he wrote. "I was too nervous to even go to the backyard afraid I’d miss the drop."

Luckily the diamond bling (2.3 carats, natch) arrived on time and the rest of the evening went perfectly.

"We both see this being a long engagement, but would love to get married within the next 2.3 years," wrote the crooner. "She will likely retain her beautiful name, but should she decide to hyphenate, Tristan Ann Prettyman-Mraz makes 23 letters."

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