The noun flux describes something that constantly changes. If your likes, dislikes, attitudes, dreams, and even friends are changing all the time, you may be in flux.
Flux can also mean being unsure about a decision. Suppose you just had a great job interview and suddenly your friend invites you to go to Australia with her. You don't know what to do because you don't want to miss a call about the job — or Sydney! You're in flux until you hear from the potential employer. Another kind of flux is liquid moving or flowing, like the flux of water under a sheet of melting ice.