I read that Smartpass thing about Erwin's letter to Marie (I don't think this was the one that I saw on Twitter and posted about before...) and...Erwin kinda implied that Nile wasn't much of a talker during their younger days. Which, in my opinion, shows that the one who made the first move was Marie. Marie indeed chose Nile rather than Erwin...as opposed to the usual, most-accepted notion in the fandom that Nile "stole" Marie from Erwin (which is pretty rude on Erwin and Nile's relationship, btw). Nile, being the quiet person he is, just accepted her advances...though I'm sure he's conflicted if he had assumed that Marie would had preferred his best friend, who had presented himself well enough for a woman's admiration...compared to himself. And I guess those advances paid off? Nile eventually married Marie, though his non-talkative side is not helping him much in telling her that his feelings are always mutual. So Erwin had to help him in that once in a while...which of course, sorta made Nile's assumption that his boyfriend DOES have a thing for Marie, truer by the years. So yeah. A quiet, emotionally suppressed Nile. I can see that. Totally.