Zeke felt like he's been living under a rock the whole time.
He really has little to no idea, and his head simply can't decipher most of their argument. But even then, he knows that it's a heavy subject - one that makes him feel guilty for not poking his nose on.
He has long been sensing that Eli is going through something bad lately, and even though he tried to lend a helping hand in his own candid way, the fact that she'd often close herself off made him hesitate every single time. Now that the two of them unknowingly slapped the real situation on his face, he realized how dumb he was for not reaching out to her sooner.
Everything that involves Eli these days is something like a sensitive topic for Noah. Zeke thought he should've known and taken action just from knowing that. Earlier when they found Lance together with her, the blonde even went as far as bolting out his frustrations to him - an upperclassman who is also one of his closest comrades.