PhD Dropout Applying to Unrelated Master's Program. How to explain it on SOP?
Tell the truth - whether that be it was too hard, you lost interest, you had a disagreement with the adviser, it was a financial hardship, you had personal or family issues come up, etc. etc. Whatever the reason, just tell the truth. The admissions committee have probably read enough personal statements to read between the lines. Sort of like how in a job interview if you said "I left because it wasn't a good fit", chances are you had a disagreement with your boss (or something like that).