Keith Urban Not Dropping Songs From Show, Setlist Changes Night to Night

Keith Urban isn't intentionally leaving Nicole Kidman songs out of his shows, despite reports ... he's simply an artist who likes to keep his shows fresh.

Here's the deal ... during Urban's show in Hershey, Pennsylvania on Thursday -- his first since Kidman filed to divorce him -- he apparently didn't play his song "The Fighter."

As you may know, "The Fighter" is a song Keith wrote about always standing by Nicole's side and fighting for her when she's not able -- which, given their relationship troubles, has received a ton of attention online from fans.

Well, multiple outlets took the one detail and ran with it ... assuming it was an intentional decision -- as if Keith was throwing shade at Nicole and their relationship troubles.

However, a source close to Keith tells TMZ ... he changes songs from night to night to keep the show fresh.

Basically, this isn't an intentional diss at Nicole ... and, Urban will eventually put the song back in the rotation -- perhaps as soon as his show in Bristow, Virginia tonight!

Remember ... "The Fighter" has already landed Keith in some hot water -- 'cause he did change the lyrics of "The Fighter," and even pointed to guitarist Maggie Baugh back in April before the line, "I was born to love you."

We broke the story ... Nicole and Keith separated earlier this year -- Keith's idea, Nicole wanted to make the marriage work -- and, they've been living in separate Nashville homes for the past few months. Our sources say they think Keith's going through a midlife crisis.