Word describing the reversal of emotions
Solution 1:
There are some good answers already, but to pitch in.
Cyclothymia could also be considered.
BUT! It might be more appropriate for:
- Mood swings (rather that emotion swings)
- A more severe/serious condition.
But it does fit to:
drastic switching of emotions
Solution 2:
mercurial
[mer-kyoor-ee-uhl]
–adjective
changeable; volatile; fickle; flighty; erratic: a mercurial nature.