The loop starts:
He loses trust with everyone including Emilia, and they leave him in the capital.
He sinks into depression, but the only person who didn't leave his side is Rem, who displayed her unyielding love by continually caring for him.
He trains under Wilhelm, who is under Cruche's (one of the candidates) orders. He learns that the Roswall's mansion is in danger, and hurries out to get back to Emilia, breaking yet another promise.
But the road back to the mansion is hazardous due to appearance of the White Whale of Gluttony.
In his attempt to get back to the mansion he and Rem are captured by the Cult of the Witch, an evil cult who worship Satella the Witch of Envy, and schemes to bring the Witch back into the world.
Here's where the hell starts: 25 chapters of constant death, torture, and unspeakable horrors by the Witch Cult.
Subaru and Rem are tortured, mutilated, and killed by Betelgeuse, the Bishop of Sloth.
After many deaths and revelations Subaru starts to formulate plans to save everything. He works to redeem himself in the eyes of everyone who shunned him.
He eventually wins the trust of several Queen candidates, and forms an alliance with Julius, the knight he lost duel to, Wilhelm, an elderly swordsman under Cruche, and beastmen mercenaries working for Anastasia (another candidate).
The group heads out first to destroy the White Whale who is blocking the passage to the mansion (~30 chapters dedicated to this). Wilhelm has a beef with the said Whale, for losing his wife many years ago.
The battle is very fierce and those who were eaten by the whale are ERASED from the world. History, memory of them, everything. No one, not even family, remembers them from ever existing. However, for some reason Subaru can remember them.
But after several deaths and loops, the group finally downs the whale.