Well, that was fast ... Bella Vaughn and Hunter Johnson from TLC's "Unexpected" have split less than a month after announcing they were planning to get married.

16-year-old Bella shared the relationship update on TikTok ... revealing she and 14-year-old Hunter are no longer together after their whirlwind engagement sparked plenty of buzz online.

While Bella clarified there wasn't some massive scandal behind the split, she claimed Hunter lied to her and hurt her feelings ... and she said the relationship had simply run its course.

If you don't know ... "Unexpected" is a reality show that follows teen pregnancies and parenthood, which means -- you guessed it -- the young teens have a baby of their own. Hunter was only 12 when Bella got pregnant with their son, Wes.

The split comes as a surprise considering the couple was celebrating their engagement just weeks ago ... when Bella proudly showed off her ring and shared an emotional message ... "the best thing about my left hand... is a ring on it from the right man."

Despite the breakup, Bella says the two remain committed to co-parenting and are moving forward on good terms.

As viewers of "Unexpected" know, Bella and Hunter's relationship has played out in front of TLC cameras during Season 7. The pair became one of the show's most talked-about couples after becoming parents at an unusually young age.

For now, it looks like the wedding plans are off the table ... another unexpected twist for Bella and Hunter.