WHIMSICAL

capricious

fanciful

determined by chance or impulse or whim rather than by necessity or reason
SYN - capricious, impulsive
"The victim of whimsical persecutions."

"He had simply been the victim of her whimsical passion - which he should have seen coming and never tied his self-worth to her passion for him."

"Leading such a whimsical life was like asking to fall since an unexamined life is not worth living at all."

"How had he gotten himself entangled in her whimsical fantasies."