The final, tragic separation between the prophet and the first king of Israel stems from deep sadness rather than anger. The prophet ceased his visits to the king not out of rage, but because he was actively mourning for him [ביאור שטיינזלץ]. Samuel harbored a profound love for Saul, viewing the monarch as his greatest achievement and the very first king he had personally anointed. Consequently, Saul's downfall and ruin caused the prophet immense sorrow [אברבנאל]. This grief was compounded when Samuel realized that God regretted crowning Saul and did not alter His decision despite the prophet's mourning. Overwhelmed by this sadness, Samuel stopped appearing before the king [מצודת דוד].
The finality of their separation until the day of the prophet's death presents a narrative challenge, as the two actually cross paths later in the biblical account. Commentators resolve this apparent contradiction in several ways. One approach suggests that the timeline implies they never met again while Samuel was alive; however, after the prophet passed away, he did indeed see Saul when a medium brought his spirit back [אברבנאל].
As for the specific later encounter in Naioth in Ramah, where Saul prophesied in the prophet's presence, the separation is understood as a change in initiative. Samuel simply no longer traveled to the king's home as he had done in the past. The encounter in Naioth only occurred because Saul sought out Samuel, not the other way around [מצודת דוד, אברבנאל]. Alternatively, it is possible that even during that unexpected meeting in Naioth, Samuel deliberately hid his face so that he would not physically look at the king [אברבנאל].