In the context of a relationship, a side quest is not a commonly used term. However, in video games, a side quest is an optional quest that is not part of the main storyline but can be completed for additional rewards or to explore more of the games world. In some games, side quests can involve developing a romantic relationship with a non-playable character (NPC) . These romance side quests can range from a series of dialogues with the NPC to a full-blown quest, and may or may not involve sex upon completion. However, it is important to note that this definition of a side quest is specific to video games and does not have a direct correlation to relationships in real life.