Here are the nominees so far for the outstanding romantic couple in anime.
Jinto and Lafiel (Crest/Banner of the Stars)
Keiichi and Belldandy (Ah! My Goddess)
Giroro and Natsumi (Kerero Gunsou)
Kyouichi and Harumi (Shingu)
Ayato and Haruka (RahXephon)
Shichika and Togame (Katanagatari)
Kenji and Natsuki (Summer Wars)
Tomoya and Nagisa (Clannad)
Mikiya and Shiki (The Garden of Sinners)
Renton and Eureka (Eureka Seven)
Noboru and Mikako (Voices of a Distant Star)
Lawrence and Holo (Spice & Wolf)
Shuji and Chise (Saikano)
Shinra and Celty (Durarara)
Rosette and Chrono (Chrono Crusade)
Batou and Kusanagi (Ghost in the Shell)
Ryuji and Taiga (Toradora)
Isaac and Miria (Baccano)
Surely there are more. I’m having trouble coming up with other couples, though — Marco and Gina (Porco Rosso), perhaps? There’s a lot I haven’t watched, and I have no special interest in love stories. If you know of any worthy anime couples missing from the nominations, please mention them in the comments.
Here are a few others:
Keitaro and Naru (Love Hina)
Yuichi and Ayu (Kanon)
Shizuku and Seiji (Whisper of the Heart)
Aoba and Ko (Cross Game)
Yusaku and Kyoko (Maison Ikkoku)
Jinta and Menma (AnoHana)
Li and Sakura (Cardcaptor Sakura)
Hitomi and Van (Escaflowne)
Kyosuke and Madoka (Kimagure Orange Road)
Kyosuke and Hikaru (Kimagure Orange Road)
InuYasha and Kagome (InuYasha)
Very worthy in my world, at least;
Yukino and Arima (KareKano)
Sana and Hayama (Kodocha)
Oscar and Andre (Rose of Versailles) (not forgetting Marie Antoinette and Fersen either)
Yasako and Harakawa (Dennou Coil)
Yuu and Yuko (ef) (plenty of other good couples round here too)
Okabe and Kurisu (Steins; Gate)
At this point, I can only think of one more to add:
Sawako and Kazehaya from Kimi Ni Todoke
Taiga and Ryuuji (Toradora – titular characters!)