Eagle-eyed fans spotted the 42-year-old actress out on a jog in Los Angeles on February 12 without her wedding ring.
The mother-of-three further set tongues wagging when she shared a touching Instagram post dedicated to her "strong" female friends in honour of "Galentine's Day".
The photo - which showed the actress with her Big Little Lies co-stars Laura Dern, Nicole Kidman, Zoe Kravitz and Shailene Woodley - quickly racked up over 200,000 likes and hundreds of well-wishing comments.
"True love is the love you have for your sisters, your girlfriends, your circle of strong women… and the ones who tell you that you have food in your teeth. Happy #GalentinesDay," she captioned the shot.
"Galentine's" is a a recent tradition originating in the US which celebrates platonic female friendships the day before Valentine's Day on February 13.
It is most commonly marked by single women, leading fans to speculate about the state of the Legally Blonde star's marriage.
It's been quite a week for Reese since she hit headlines for all the wrong reasons on February 9.
The Walk the Line actress took a tumble down the stairs as she left pal Jennifer Aniston's 50th birthday bash on Hollywood's Sunset Boulevard.
Reese gripped onto the hand rail for support before being helped to her feet by hotel staff.
Reese and her 48-year-old talent agent husband started dating around January 2010, shortly after Reeses' split from fellow actor Jake Gyllenhaal.
Jim got down on one knee less than one year later with a $250,000 4k Ashoka diamond and they tied the knot in an intimate ceremony at Witherspoon's mansion in Ojai, California.
The couple share 6-year-old son Tennessee James, while Reese is also mother to son Deacon, 15, and lookalike daughter Ava, 19, with ex-husband Ryan Phillippe.