Butterfly effect...

That the flapping of a butterfly’s wings in one place can affect the weather in another place

or more known for

The sensitive dependency on initial conditions, to where you can simply say as a condition to where how a small chance can affect large complex system..

And like the butterfly effect..

Every little things she did.. in the end, effect her greatly.. to where when she realized...

She is drowning too deep to be saved...

Falling too hard to be up...

and just..

Perfectly in love with her bestfriend...