I think you're in need of a reread child. I forget so much in the span of a month as well.
Marley convinced the world to wipe out all Eldians without exception due to a conflict that happened over 1000 years ago. Eren realized that the world will never stop trying to kill all Eldians and decided that he will do absolutely whatever it takes to protect his family and friends, so he's apparently willing to wipe out the whole world except for Eldia in order to protect his people. His friends don't want to be protected this way, so they've teamed up with Marley soldiers to stop Eren while those loyal to Eren and his cause are trying to stop them.
Personally though, I think Eren has another plan in mind, like he's trying to pull a Lelouch or something. His actions and words prior to unleashing the Wall Titans indicate this, and Armin seems to have an idea of what Eren is actually trying to do too.
Wow thank you, this helped a lot. And YES, i couldn't have exolained the Eren situation better.I bet he's pulling a Lelouch on us too sadly
I don't understand shit. I don't know whose is on whose side anymore, it's sooo confusing. I just know that at then end Eren will die, i feel it in my bones