Synonyms: inconstant
Definition: likely to change frequently often without apparent or cogent reason; variable
Usage: inconstant affections; an inconstant lover; swear not by...the inconstant moon- Shakespeare
Definition: (used especially of persons) not dependable in devotion or affection; unfaithful
Usage: a false friend; when lovers prove untrue
Similar words: volatile, fickle
Definition: marked by erratic changeableness in affections or attachments
Usage: fickle friends; a flirt's volatile affections