Answer:
You didn't stipulate in this question if the relationship was an intimate one. There are all kinds of relationships. Even so, most relationships imply there is love at some level present. So I would say that affection is present in relationships that involve a person or persons that care for each other in some way. The way that affection manifests itself is subject to the environment of the relationship and thus varies based on the conditions.
You can have affection for another that you only admire or fancy and not have have a relationship in the sense that it was previously spoken about, but you have still formed a relationship to that person in your mind.