It's most likely a simple case of the game following two paths which were intended to be mutually exclusive, due to scripting bugs. Same deal Lena in relationship with Ian could have a threesome with Louise and Jeremy, despite the game earlier preventing Lena/Ian from happening with earlier Lena/Jeremy hookup.I assume it was a bunch of loose ends, where the writing hasn't yet accounted for that specific path and is using text from other paths.
One path is unattached Holly who learns to have fun, the other is Holly in relationship with Ian.