Gwen Stefani's been directly associated with selling over 35 million albums in her 35-year musical career. However, one thing will likely elude her: a hit single written by her fiance Blake Shelton. As she recently told DJ Khaled while a guest on his The First One podcast, "I wish he would write with me, but he doesn't really write anymore."

This year marks four years since Shelton released gold-selling album Texoma Shore. As far as new music -- notably from him and his famous fiancé, Stefani noted that they had previously written a Christmas song and two other songs together that remain unrecorded.

This is not to say that Stefani and Shelton have not previously collaborated as songwriters. Their first duet, "Go Ahead and Break My Heart," was released in May of 2016, while they have also recorded alongside Justin Tranter and Busbee for 2017's "You Make It Feel Like Christmas," released from Stefani's holiday album that shared the same title.

As for vocal collaborations, the duo has proven wildly successful to date. They have achieved back-to-back number-one country radio hits with "Nobody But You" and "Happy Anywhere." Both of these were written by outside writers.

Stefani also has her fifth solo studio album forthcoming, for which she'll "lean on [Shelton] heavily" in creating. On December 7, Stefani released a new single for this proposed album entitled "Let Me Reintroduce Myself." As well, she has teased three other singles: "Slow Clap," "When Loving Gets Old," and "Cry Happy."

However, nothing still from her soon-to-be husband. "He has a really good ear for hits or just songs that are the ones that we all like," Stefani adds to DJ Khaled. Laughing, she continues, [Shelton] just doesn't like writing that much. It makes me so mad."