An explanation for those that are confused as to what's happening.

Ok, we can all agree that Attack On Titan is great, but the plot has gotten very complex and very confusing. This is what I'm able to conclude based on my understanding of things.

Long ago, the Marleys tried to take over the world. Eldians fought back when the original Ymir supposedly made a deal with the devil to gain titan powers, from which the 9 titan shifters came from. Using the titan power, they fought back the Marleys. The Marleys then used the fear of the Eldians' titan power against them, by making them out to be a threat to the world, labeling them as "devils". With the world turned against them, the Eldians sealed themselves in the 3 walls, created by several Colossal titans, threatening to unleash them on the world if the world didn't leave them alone.

The Eldian royal family decided to keep the Eldians within the walls by erasing everyone's memories of the war and the outside world. The power of the Founding titan is held by the king, and is passed down through the generations by having the heir become a titan and then devour the previous ruler to inherit their memories and will.

Over time, the Marleys still seek to destroy the Eldians and obtain the power of the titans for themselves. They do this by brainwashing the descendants of the Eldians (Gabi and the others) left behind into believing they needed to kill the rest of the Eldians. Somehow, they managed to get the power of most of the titan shifters, which they have been forcing on the brainwashed Eldians into fighting for their cause.

Eren's father sought to stop the brainwashing of the Eldians being used by Marley. When Zeke discovered this, he turned him over to the government. The Marleys have been turning anyone disloyal to them or who are enemies into titans and sending them to Eldia. Dr. Yeager managed to escape and fled to Eldia without getting turned into a titan.

Initially, the Eldians thought the world behind the walls was purely titan infested due to their memories being altered. They knew nothing of the war, and only wanted to kill the titans. Since the royal family was refusing to allow the Eldians their freedom and kept them subjugated in the walls, Eren's father stole the Founding titan's power and killed most of the royal family. He then passed this power on to Eren when his time was running out.

The Marley sought to get the founding titans power so they could wipe out Eldia. They sent the current holders of the titan powers to destroy the walls and find the holder of the Founding titan's power, but along the way, one was eaten by a titan (Ymir). Reiner and Bertolt destroyed several walls, letting the titans into Eldia, then they join the army while they searched for the Founding titan and Historia, since only a member of the royal family can truly control its power.

Eren and his friends enlist, and Eren discovers his titan power. Annie, Reiner, and Bertolt realize Eren has the founding titan's power. Annie tries to abduct him, but fails and is captured. Reiner and Bertolt try to convince Eren to surrender himself by promising not to hurt any of his friends. This fails, so they abduct him, along with Ymir (who was revealed to be the titan who ate their friend, thus becoming the Jaw titan). They plan to capture Historia later. Eren is rescued, and Reiner and Bertolt return to Marley with Ymir, who is eaten and has her titan power passed on to someone else. A bunch of battles happen following this, in which Zeke reveals himself as the Beast titan.

In Eldia, the royal family tries to reclaim the Founding titan power by attempting to make Historia into a titan and then eat Eren. She refuses, and the rest of the royal family is killed off when her father becomes the Super Colossal titan. Meanwhile, the false king of the Eldian, who had taken over after Eren's father killed the royal family, and the corrupt governors are dethroned, and Historia becomes queen.

More battles follow. Armin is turned into a titan to save his life, and then eats Bertolt, becoming the new Colossal titan, inheriting Bertolt's love for Annie in the process. Then comes the time jump. At some point during it, Eren meets up with Zeke and the two form a plan to stop the war. Eren then goes awol and infiltrates Marley to learn all that he can. During this time, we meet Gabi and her friends.

In an attempt to focus all their efforts of capturing Eren, the Marley leaders reveal that most of the history that was taught was a lie, and that the only true "devil" is Eren, not Eldia itself. Eren then reveals himself, kills several of the Marley leaders, and eats the holding of the War Hammer titan. The Eldians then arrive to rescue him. Gabi and Falcon stowaway on the ship, and Gabi kills Sasha. Zeke is revealed to have been a traitor to Marley by having helped Eren, who is his half-brother.

It's revealed that during the time jump, Eren has gained a following. His goals now seem different from that of his friends, including Armin and Mikasa. He's labeled as an enemy of Eldia, as it seems like his followers want him to rule. For unknown reasons, Eren severs his ties with Mikasa and Armin, claiming that Armin is just a slave to Bertolt's influence on him, and Mikasa is a slave to the Ackerman gene, which is what makes her so devoted to him. He then has them and the rest of his friends locked away since they're supposedly enemies now. They suspect that Eren has a reason for doing what he's doing though.

Yelena meets with Armin, Mikasa, and the others and reveals Zeke and Eren's plan for peace. As long as there are people who can become titans (as only Eldians can), Zeke intends to end the war by having the Eldians slowly die out by not letting them have children. He believes that while the Eldians are not evil, they're still a threat since they can become titans. So he intends to put an end to the war by having Eren devour all the titan shifters, stop the fighting, and then let the Eldians live out the rest of their lives in peace, but not allowed to have children.

Eren supposedly agrees with Zeke and is going along with this plan. As does Armin, though it's possible he may have figured something else out, as he's relieved by Eren's actions up to this point, so it's possible that Eren is planning something else. Marley is still trying to steal the Founding titan's power, thus leading to the sneak attack we saw in the latest chapter.

Hope that clears everything up. And again, this is just from what I understand, and I could be missing some things or misunderstanding some things.