Alexander had a big choice to make , as continuing to explore the ruins would mean that he would be unable to return to his territory for a long time . However after making up his mind to turn back he realised that his heart would simply not allow him to turn his back on a happy future for Ronan.
He tried to be an upright king , he tried to do his best for his citizens who were like his own children for him. However compared to his own flesh and blood they finally paled in comparison.
Reason suggested Alexander to go back , however when he thought about Ronan's struggles and Sierra's tears when she missed him , Alexander knew that the only way to make his family whole again was by getting that ring.
Finally the family man Alexander won the duel over king Alexander and he decided to delve deeper into the ruins , even if it meant that he would be gone for years.