After hiding Eren's POV and internal monologue for the entirety of post-timeskip, Eren finally breaks down and reveals his intention to a child who cant understabd him and will be killed by him in the future.

It makes no sense from a writing perspective for Eren to lie or hide anything here because he is basically pouring everything out to a wall. So if his motivation was wife and child, 131 was the chapter(named Rumbling) where he should have revealed, if friends was his primary motivation then also it should have been revealed in 131.

Personally I had no problem understanding Eren's true motivation being his sense of entitlement over the scenery and my bias for EM definitely didnt get in the way of my reading comprehension so I can only blame others for being too invested in their fanon version of characters if they didnt Eren's motivation right after 131.