She was there longer, and on the point of a bit of a breakdown when Shinji showed up on account of 'effectively a lone canon warrior for a couple years.'
(There was a Ken for a while, but he was Regular Timeline; Junpei for about two seconds, who was 'Regular Timeline but CRAU from a game that had a FemC; and about a million P4s of varying levels of canonicity.)
Shinji did reach a point where not owning up to his crush was becoming the bigger regret, and made her chocolate, but she never responded (which he kind of expected and is okay with).
They also both ended up immortal thanks to one event (Shinji will be fucking relieved that seems to be off the table now...) and were accordingly going 'well now what.'
and would be the easy choice if this was Naoki, but it's not.Shinji: Food.