ayo us bros also enjoy good shojou mangas.
First, did their string only disappear, or just her powers!?
Second, if it's only their string will she trust the love without a red string? Like it won't last, like her parents.
So troublesome, she says that the string manipulates them into liking each other and she doesn't want to believe in that kinda love, then she believes that since the string doesn't exist, there is no love, can't she see it's contradictory.
Anyways her worries should cease to exist now though, since it was proven that a string can appear outta nowhere and that it can disappear too. Means there are peoples feelings involved, though her kinda seeing it kinda mess it up.