You have two options, use an SSD, or disable it. Since you don't want it to use the HDD to read data from, there is no option but to disable it since you are not using an SSD.
I'm curious as to how this problem occurred
It isn't a problem. It is how it works. After a while of using your PC it fills up the RAM with files that are frequently used. 32GB of random files takes a while to load. It also will remove/add new things on the fly. If you open a program that isnt preloaded it has to write a bunch of stuff to disk to make room in RAM for the new application. For the majority of people it works great as the most common use for a PC is web browsing so there isn't much to load, just the browser and a few other files for quicker access.
If you do a lot on your PC there is a lot more to load and swap on a regular basis.
how disabling superfetch will affect me
Disabling it has no real effect other than making your most used programs load normally (instead of being fast due to being in RAM).
and whether there is a way around disabling it.
Use an SSD.