Maci's ex Ryan has never been one to show his emotional side when he chronicles his Teen Mom OG life -- until now.

In a sneak peek from Part 2 of the reunion special, below, Dr. Drew speaks with Ryan's new girlfriend Mackenzie -- who joined Ryan, Ryan's mom Jen and Maci on stage -- about the fight her boyfriend had with his father Larry. While at first she is resistant to address the non-televised disagreement, the young mother eventually opens up about the difficult incident and the effect it had on her partner.

"One day, he just woke up and was like, 'I need to apologize to my dad,'" Mackenzie recounts.

And when Bentley's father remembers the aforementioned incident before the reconciliation, his voice begins to crack and his eyes well up with tears.

"I see you having real emotion here," Dr. Drew states.

But he's not the only one who cries during this poignant moment. Watch the heartfelt scene in the video, and don't miss the entire Teen Mom OG reunion special on Monday at 9/8c.