How to be the Childhood Friend of a future legendary hero

A man is chosen by God after dying to become the hero's childhood friend and get him so hooked on her who swears to return to his side, promising rewards. Despite finding the situation absurd, the consequences of rejection are such that he decides to accept and, thinking that the hero was from a game he knew well, he thought it wouldn't be too much of a problem. However, the situation becomes complicated in unexpected ways...through her own fault. After all, how can you easily become the most important figure of the future hero if you allow other girls to have the same opportunity to compete for the position, after wrongly awakening his passion for the beauty of women?