Arbeloa stepped up from Real Madrid Castilla, the club's reserve team, after Xabi Alonso was sacked in January following just seven months in the dugout.
Los Blancos have gone from bad to worse since, with behind-the-scenes issues impacting performances on the pitch. Real were on the receiving end of a 2-0 defeat to Barcelona in last weekend's El Clasico, as Hansi Flick's men confirmed the LaLiga title would remain in Catalonia.
It's the second successive campaign where Real have gone trophy-less, and in an attempt to change the narrative, Mourinho is set to return for a second spell.
The Portuguese boss won three domestic trophies between 2010 and 2013, including the 2011 LaLiga title with a record points total. But this is set to be an even greater challenge than last time, with Mourinho set to enter a fractured dressing room.
Fede Valverde's hospital trip following a fight with Aurelien Tchouameni is just one of several problems creating a disconnect within the squad, and the Real hierarchy are hoping his experience will help transform the mood.
According to The Athletic, Mourinho is set to meet with Real president Florentino Perez next week after agreeing on personal terms to return.
The 63-year-old is set to sign a two-year contract in the Spanish capital after already informing Benfica of his desire to leave.