Left In The Dust(Ereri/Riren)

Eren and Levi have been dating since seventh grade. They love eachother. Everything about their life seems perfect. But one night that all changes. Eren cheats on Levi, or at least. That's what Levi thinks.
Eren has to battle with depression and gruesome nightmares from that night. His friends all turn against him. Where's he to go? The only person he knows will listen. Marco.
Its up to Marco and Eren to find a way to force Levi into hearing the truth. Will they succeed? Or will Eren be left in the dust by the one person he thought he could trust?