I dunno, i know it completely ruins the story but wouldn't it of been easier for them to open the door to the two "cheating" and then make their own thing official, it kind of is hard to believe you justify their cheating by doing so yourself. Also by the end the two "new" couples are together more than the old, That said, I kind of support Reiji and Asuka but not Kanade's couple, Kanade's side was just cheating for cheatings sake, dude barely made a move and she went along, also spent most the scenes comparing to Reiji, feels like she only finds the emotional side of Reiji attractive by the ending and only loves the other guy for sex, effectively making her lesser. Asuka and her husband don't get on but her and Reiji feel more like a actual couple, shame they don't just call it and get with their new partners, seems everyone would be happier.