I think their relationship was set. In episode 22 Okabe confessed to her and there were at least 4 kisses (on-screen at least), later she came back to say "I love you" back, but she couldn't.
Then in USA he confessed again, even with that amazing line, she did the same, they did "that thing." One year later they had the drunk Kurisu moment, and the goodbye at the train station, with more kissing.
Of course, the relationship was kind of slow becase all the experiences she had were from the other timelines, those are now fragments of memory, she experiences them as dreams but she can't deny her feelings. Also, Okabe doesn't wan't to push that much even when he confessed twice and asked her what she felt.
Due Okabe's social awkwardness and Kurisu's kind-of shy self and tsundere nature their relationship progressed (after episode 24) kind of slow (considering all they have gone trough). But I truly believe there's nothing else in the middle, they love each other, they are just shy of admitting it to each other in public because they don't like to express their real feelings. You can see that from Okabe treating Kurisu disrespectfully and calling her assistant, nicknames and hiding the gift he was gonna give her, heck, even not mailing her or calling her in a year (I don't understand this). And her, well she's also shy, even when she was giving him a new coat. When she invited Mayuri back in episode 25 to USA and she wrote that Okabe didn't need to come with her, becase she didn't want to see him ("tsundere as always" - Daru)
If the relationship went well after this was up to them, they really have something precious (they even went in and out of hell to bring each other back). Sure, Kurisu maybe went back to USA to continue research or whatever she does there, but I'm sure this time they kept contact and who knows? Maybe she got to move back to Japan. I think there was nothing stopping them, they even have Mayuri to help them with the honesty =D
I mean, a recap:
Episode 22: He confessed, they kissed, she was going to say "I love you" back but she couldn't
Episode 24: She, against all odds, went back to Japan to find Okabe and thank him, but even "remembering" stuff (The "I told you I'm not Christina or your assistant!")
Episode 25: She being tsundere about him, being jealous, he confessing to her again, and they kissing again.
If you don't count the movie they even got 3 confirmations before this. So, OkabexKurisu couldn't be more real.
And if any of you would like some OkabexKurisu reminder, or are not sure about how it ended, take a peek!
Episode 22
Episode 24
Episode 25
Movie
Just some of them, those were the ones I knew location, others I don't know in what episode they are or even where exactly in the video. |