"[Fedotowsky] has to forget about Vienna and worry about herself," Harrison toldUs Weekly in a Tuesday report.
"[She needs to realize] 'Enough with the bickering, enough that the cattiness. If I'm going to do this, I need to be with [Jake Pavelka]. If Jake likes [Vienna], then so be it. I can't judge why she's here, and I just need to take care of myself.' The quicker she realizes that, the better she will be."
Fedotowsky and Girardi are two of the four remaining bachelorettes vying for Pavelka's heart on The Bachelor: On the Wings of Love, and Harrison described them as "two of Jake's favorites."
"They know that. The funny thing is, as you'll see, those two are beating each other up so bad that [Tenley Molzahn] is just skating through the door," Harrison told Us.
"Tenley is so sweet and maybe she doesn't outwardly show it, but I think she realizes, 'Hey, you guys keep fighting amongst yourselves!'"
Harrison added that Fedotowsky and Girardi "think that they are different, but they are really not."
"I mean, their personalities - on the surface - appear to be different, but they are really caring, loving people," explained Harrison to Us.
"It's funny because they think, if Jake likes Vienna or if Jake likes Ali, he can't possibly like me, but in actuality they don't realize how similar they are because obviously they don't get to see how they are on a date, so it's really kind of ironic. We get to see behind the curtain so we know that, but they don't."
The Bachelor: On the Wings of Love's next episode -- in which Pavelka will visit the hometowns of his four remaining bachelorettes -- will air Monday, February 8 at 8PM ET/PT on ABC.