There's a simple explanation. The future is not set in stone. Anything you see can be changed, foresight is just a prediction. What you see will only occur if you continue as if you did not see it (i.e. stay on the current path).
Time Travel spells are not possible on this plane, if there are certain abilities that you can have to see the future. But yet you can't predict the future because it will always change no matter what you may see.