'Teen Mom' Star Amber Portwood Reports New Fiancé Missing, Police Investigating

"Teen Mom" star Amber Portwood says the man who recently proposed to her has since disappeared ... and now cops are involved.

Portwood beelined it to a North Carolina police station Monday and filed a missing person report for her new fiancé, Gary Wayt -- who just popped the question a few weeks ago, to which Amber said yes.

According to the incident report, obtained by TMZ, Amber told police Gary was last seen Sunday evening at their hotel. She notes Gary isn't a resident of the area ... he's from Indianapolis.

Anyway, the Bryson City Police Department is now actively investigating the case ... and cops are asking for the public's help in tracking down 39-year-old Gary.

Police say the reality TV star's fiancé is described as 6-foot-1, 205 pounds, bald, with brown eyes ... and he's driving a grey 2009 Nissan Rogue SUV with Indiana license plates.

The timing here is interesting, to say the least ... Amber just introduced Gary for the first time on "Teen Mom: The Next Chapter" in Thursday's episode on MTV ...  and 72 hours later she reported him missing.

Amber and Gary reportedly got engaged within the last 3 weeks ... and first got together in 2023 after matching on a dating app.