I think I finally have understood HOW  splitting works. So, I will bring example:  Im either super organized,  careful and productive or... or just a mess , pure  mess in everything.
And now I’m on that stage where I understand I have to get myself moving to become organized.And in my mind I start to visualize what should I do to build, to own this another personality of mine , so when I think about what should I do it’s getting hard ,because I realize I abuse myself to do a lot of things before staring my productive day  ,like clean my room until it’s literally shines , wake up at 6 o’clock, having strictest schedule and even looking perfectly .All those requirements I’ve created are necessarily to have the desired organized personality and now I’ve got answer why . 
   Just  because I HAVE to do something hard I feel like I HAVE to complete a whole list of things that are not that easy to do , that the lazy personality would never do so the reason is because I have to DESERVE having the desire to personality. I abuse myself to deserve it first And then I can be . So basically it’s all about feeling not good enough. so what happens when from organized personality I switch into the messy one , easy. A simple slip,  something went wrong and i can’t change it so i cautiously  pretending that this is how I want to be , this is how supposed to be , so to reassure that,  I start to destroy everything around and pretending that this is what I want so I will not feel uncomfortable that something goes wrong

I don’t know but for me it’s like opening eyes a little bit , even though I don’t know how to use it yet I haven’t come up with any successful and less harming pattern just I’m thinking it’s probably pretty much how it is , i might be even very wrong , so let me know what you think  or if  you can relate. PEACE ✌🏻