Kristen Wiig is engaged.

The 45-year-old actress and her partner of three years, Avi Rothman, have reportedly been engaged for several months but have not yet announced their happy news, TMZ reports.

Kristen has reportedly been sporting a huge diamond ring on her left hand for the past few months.

Kristen and writer, actor, producer and director Avi have kept their relationship quite private but the pair were first spotted together on a romantic vacation in Hawaii in May 2016.

The actress was previously married to actor Hayes Hargrove from 2005 to 2009 and, in 2011, Kristen ruled out ever tying the knot again.

She said: ''I probably won't ever get married (again), it's not something that I would want to do. [In the movie 'Bridesmaids' we were careful] to not send the message that you need to get married. ''I think women put that pressure on themselves, maybe even more than society does, but, if you're the single girl at the wedding, you know someone is going to ask you when you're going to get married''.

Meanwhile, it's a busy time for Kristen who has reunited with her 'Bridesmaids' co-writer Annie Mumolo on a new comedy.

The actress and comedian - who penned the Oscar-nominated comedy script alongside 45-year-old Annie - has re-teamed with the 'Joy' scribe to create a new Lionsgate film, 'Barb and Star Go to Vista Del Mar'.

The pair are also co-starring in the film, which is being helmed by Josh Greenbaum, while female-focused production company Gloria Sanchez Productions - founded and led by Jessica Elbaum, Will Ferrell and Adam McKay - will produce alongside Kristen and Annie.

The movie tells the story of best pals Barb and Star (Wiig and Mumolo), who find themselves tangled up in a villain's evil plot to kill everyone in town after leaving their small midwestern town for the first time to go on vacation in Vista Del Mar.

In a statement, Greenbaum said: ''I'm so excited to be a part of this movie which showcases Kristen and Annie's original, fresh and undeniably hilarious voice in spades, I'm also always looking for projects with titles that rhyme, so it really all worked out on this one.''