Akai Hitomi no Seraph

Kengo and his lover Ai are in a relationship for two years, but they never were intimate with each other. Even when Kengo's parents go on a trip his suggestion is rejected by Ai. Kengo tried to summon a love angel with a spell, but failed with it. As a result, love of this world was confined and in order to save love he needs to enter the spirit world, interact with its inhabitants and rescue love withing a limited time period.

[From vndbreview]