Jax, 40, is no longer following them on social media, but it's unclear whether he made the first move or whether they blocked him.
All three are still following Jax's wife Brittany Cartwright, 30.
Tom, 36, served as co-best man at Jax and Brittany's wedding on June 29 in Versailles, Kentucky, but it appears their friendship has hit a snag.
Kristen was noticeably absent at Stassi's engagement party in July, and Stassi's mother Dayna confirmed their fallout when a fan asked her if there was tension.
"Yes, quite sad. But I didn’t really know all the particulars. So I was out of the loop for awhile. Don’t you worry, it’s like Lion King and the circle of life … each one of these girls will grow, change and come back to their original strong friendship bond that they’ve always had. Somethings just take time," Dayna wrote.
What do you think happened between Jax & his costars? Sound off in the comments below!