Changeable, Unpredictable, Inconstant
Puzzle 6 of Love Songs Pack
Question is: Changeable, Unpredictable, Inconstant
and the answer is: MERCURIAL
Word Meaning:
MERCURIAL — (obsolete) Any of the plants known as mercury, especially the annual mercury or French mercury (Mercurialis annua).
Definitions from Wiktionary.