The sixth run of the ABC romance reality show will see former Bachelor favourite Fedotowsky - who appeared on Jake Pavelka's season - trying to find love among 25 potential suitors.
Speaking to US Weekly, the host teased that fans can expect to see a "phenomenal ending" to the competition.
"Whether it's happy or not, I'll say this, Ali had to make a very tough choice at the end, several tough choices, and I think she's satisfied with how it ends and satisfied with her choice."
Harrison also suggested that Fedotowsky had a "fear of almost being rejected" when she began her journey, and that she is a "girl that has in the past been hurt before".
He added: "The more I got to to know her, the more I realise she's this strong, independent, beautiful woman, but very vulnerable."
ABC previously released preview clips from the new season which feature Fedotowsky saying that she is "ready to find love".
The Bachelorette premieres May 24 at 9/8c on ABC.
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