Eh, as someone who is deeply invested into psychology; where a lot of this "fluid" and a billion other terms that exist come from, I don't really believe it's a real thing. Technically speaking everyone would be "gender fluid" and it in itself is a relative term that varies from person to person. For example shopping for a man could be considered female and he may consider himself feminine for that period of time or remainder of the day as a result or vice versa with whatever equivalency that exists -but to another man/woman that task could be considered a gender empowering or just normal thing. Honestly it just feels like a label for the sake of looking for different sexualities/debates about gender. But idk, personally "gender fluid" has too many variables and relativity to be a real thing to me. It may say something about how that person perceives gender stereotypes and probably takes those stereotypes too far, but thats about it
Basically this.Taking out the times that people actually are born with two sexual organs(or the mix of it), these terms that are used to describe actions and/or behaviors are just there to explain better a certain situation for conversation or study purposes.In reality, you dont "change" gender, or act like the oposite gender for a period of time, just because that said activity is more related to a especific sex.Its the same as all type of fears, behaviors or sexual preferences have names or terms to it.(for example:if you have fear of spiders you suffer of arachnofobia.But thats not a disease, since it dosent impede you from living your life.Its just a slice of your personality.).We have those infinite terms for any situation because there is not a normal, since being "normal" is determined by what the society chooses it to be.For you to be a "man", for example, you need to at least do stuff a way, and the same goes for females.But that is only accepted because society accepts as such.If things were different, lets say if by chance woman were stronger physically than men by nature, the definition of normal for each one would certainly be different.
Making it short:No.Its just a term to study human behavior more easily.At least, thats how i see it.