Oreimo 2 Episode 16 -

Kyousuke and Kirino face their childhood friend Manami Tamura , who opposes their romantic relationship. A physical fight breaks out between Kirino and Manami, after which Kyousuke definitively chooses Kirino, ending his lifelong friendship with Manami.

Kyousuke and Kirino hold a private, "pseudo-marriage" ceremony at a church. They share a kiss, which many fans and interviews suggest was on the lips, despite the anime framing. OreImo 2 Episode 16

While the relationship officially ends, the "shared secret" mentioned at the close and the after-story titled "A Momentary Chance Encounter" imply they remain together in private. Kyousuke and Kirino face their childhood friend Manami