Will Arnett and Model GF Carolyn Murphy Break Up

Will Arnett and his girlfriend Carolyn Murphy are officially through ... TMZ has learned.

Sources familiar with the situation tell TMZ ... the actor and his model better half broke up a few months ago -- there were signs of trouble in paradise when she didn't attend the Oscars with him in March.

Hollywood might be known for its nasty splits ... but, we're told this wasn't one of them -- this is just two adults whose relationship didn't work out.

If you don't know ... Will and Carolyn confirmed their relationship back in September when they attended New York Fashion Week together.

In November, Arnett opened up about arm candy ... saying her generous spirit was just one of many things he loved about her.

Arnett has been part of many high-profile relationships over the years ... previously dating stars like model Alessandra Brown and actress Penelope Ann Miller. He married fellow comic star Amy Poehler in 2003. The two separated in 2012 and finalized their divorce in 2016.

Carolyn was married to businessman Jake Schroeder from 1999 to 2002. The two share a daughter.

We reached out to reps for Will & Carolyn... so far no word back.