I mean, what do you expect? It would be pretty unsatisfying if, after all their mutual pining, Evans ended up getting together with a random groupie who's only been in two chapters. It's like with Shiragami in
Jitsu wa Watashi wa, from pretty much as soon as she was introduced in the first volume, it's been obvious that Oakley is the true endgame, and once the two of them finally get together, the manga's over. It's not a matter of "if", only "when" and "how".