Apollo is.
He had a disagreement with Agamemnon over a girl.
Agamemnon wanted Achilles' girl (called Briseis) but Achilles refused, and was about to kill Agamemnon in anger, but a goddess stopped him, saying that killing him wouldn't solve anything, so instead he said he would leave the war - stop fighting, and that Agamemnon ould have the girl but would regret it later.
He acted like a child. After hearing that his concubine, Chryseis, needed to be returned to her father (the priest of Apollo) Agamemnon's basic response was that if he had to suffer the loss of a concubine, that Achilles should lose his too. When Achilles became irate over this loss and refused to continue fighting, Agamemnon showed him the door claiming that he could still win without Achilles. Only the death of Achilles's close friend Patroklos inspired Achilles to fight for the Greeks again.
Phthia, as he says in the first book of the Iliad in his rant to Agamemnon.
because Hector killed Achilles' friend Patroclus in a fight, when Patroclus had dressed up as Achilles so he could fight in one of the battles of Troy.(In the film Troy starring Brad Pitt, Achilles and Patroclus were cousins. In the original legends, they were friends but not related)
He had a disagreement with Agamemnon over a girl.
Agamemnon was forced to return his lover Chryseis to end the plague, and took Achilles' concubine Briseis as his own. Enraged at the dishonor Agamemnon had inflicted upon him, Achilles decided he would no longer fight.
Patroclus used Achilles armor to fight Hector when Achilles refused to continue fighting for Agamemnon. Patroclus was Achilles close friend and lover in the Iliad.
Jealousy fueled the conflict between Agamemnon and Achilles in Homer's "Iliad" when Agamemnon claimed Achilles' war prize, Briseis, after being forced to return his own prize, Chryseis, to appease Apollo. This act not only insulted Achilles' honor but also ignited feelings of resentment and betrayal. Achilles felt that Agamemnon's actions were driven by a desire to assert dominance, leading him to withdraw from battle and refuse to fight for the Achaeans, which had dire consequences for their campaign against Troy.
Achilles withdraws from battle because Agamemnon offends him by taking his concubine. Achilles states that if Briseis is not returned to him he will not fight.
Agamemnon took the Trojan woman, Briseis, whom Achilles had captured, taken as his slave, and fallen in love with because an oracle had ordered him (Agamemnon) to give up his own woman, Chryseis.
Achilles saw Briseis as his; be it as slave or wife/bride, and when Agamemnon was premitted to take what was Achilles's it said that the others valued him less and so he refused to fight in the war.
Agamemnon offers Achilles numerous gifts to appease him after taking Briseis, Achilles' war prize, which leads to Achilles' withdrawal from battle. The gifts are meant to honor Achilles' status as a great warrior and to persuade him to rejoin the fight against the Trojans. Agamemnon hopes that these offerings will mend their relationship and restore unity among the Greek forces. Ultimately, the gifts symbolize Agamemnon's recognition of Achilles' importance and his desperation to resolve the conflict.
Oh honey, Achilles was as justified as a cat in knocking over a vase. Agamemnon done him dirty by taking his girl, so of course he was gonna throw a hissy fit and sit out of battle. Can you blame him? Men and their egos, I tell ya.
Agamemnon wanted Achilles' girl (called Briseis) but Achilles refused, and was about to kill Agamemnon in anger, but a goddess stopped him, saying that killing him wouldn't solve anything, so instead he said he would leave the war - stop fighting, and that Agamemnon ould have the girl but would regret it later.
Achilles is famously angered by Agamemnon in Homer's "Iliad." The conflict arises when Agamemnon takes Achilles' war prize, Briseis, leading Achilles to withdraw from the battle and refuse to fight for the Greeks. This act of dishonor ignites Achilles' rage and sets off a chain of events that significantly impacts the course of the Trojan War.
He was in a hissy fit because his commander King Agamemnon had taken over his girlfriend Briseis.