If there is an affinity between two friends, does one then have an affinity for the other? Affinity has a variety of meanings, ranging from “relationship by marriage” (its earliest) to “a resemblance or similarity” and extending to “a natural attraction” and even “a chemical attraction.” The meanings are clear enough, but it’s not always easy to know which preposition to use for each of these senses, especially since other factors can affect your choice, such as which verb you use. Thus you might say you feel a real affinity for (or to or with) your old neighborhood, and you might also say that the affinity between your old neighborhood and the people who once lived there is strong. Thus, while all of these usages are acceptable, there are some restrictions on which prepositions are acceptable with affinity.

When affinity means “similarity or resemblance,” the prepositions with, to, and between are standard, and it’s hard to imagine a context where for would make sense. When affinity means “a feeling of kinship or sympathy,” as in I have an affinity for people in their situation, for is perfectly acceptable. In some metaphorical uses, as in writing about food, for tends to predominate: Lamb has a distinct affinity for red wines. In chemical contexts, for is the preposition of choice: the blood’s affinity for oxygen, a dye with an affinity for synthetic fabrics.