This week's episode of the ABC romance reality show saw Fedotowsky handing roses to Roberto and Chris L in Tahiti, while third contestant Frank chose to leave the show to return to his ex-girlfriend in Chicago.
Writing on his Entertainment Weekly blog, the host said: "Although it was a wild rollercoaster ride to get here, I truly believe Ali has narrowed it down to two really good men."
He continued to say that Roberto's declaration that he is falling in love with Ali was "huge" because "she's always been a little worried Roberto was too good to be true".
"Ali also heard what she needed to from Chris this week," he continued. "You can just tell with Chris that it's taken a great effort for him to get to this point, and he seems almost relieved to feel this way again about a woman."
Harrison also discussed Frank's exit from the competition, saying: "I'm not 100% sure he knows what he really wants right now in his life. I do hope I’m wrong, and I hope he and Nicole truly do love each other and find happiness together."
The Bachelorette continues next Monday at 8/7c on ABC.
> 'The Bachelorette': Episode 9 recap