Changing frequently, esp. as regards one's loyalties, interests, or affection
Web patrons are a notoriously fickle lot, bouncing from one site to another on a whim
the weather is forever fickle
marked by erratic changeableness in affections or attachments; "fickle friends"; "a flirt's volatile affections"
erratic: liable to sudden unpredictable change; "erratic behavior"; "fickle weather"; "mercurial twists of temperament"; "a quicksilver character, cool and willful at one moment, utterly fragile the next"
(fickleness) faithlessness: unfaithfulness by virtue of being unreliable or treacherous
Quick to change one’s opinion or allegiance; insincere; not loyal or reliable