What if she was a rebound after all and he didn't feel the same way for her anymore?

to switch off a train; to switch a car from one track to another

These studies indicated that variations of the IIP-MF projections...were probably associated with a physiological process inside the hippocampus causating behavioral differences in spacial learning and exploration.

[…] You ought to try one of these biscuits. They're good. I've not long had breakfast, Morgan told him.