You super dumbass. Single people have affairs all the time. Sadly in your world it appears adultery is more common than single people getting it on. There is no definition of "affair" that means the two people involved cannot both be single. There is also no definition of "affair" that says one or both people have to be guilty of adultery.
You Stinking Whore: Single people go on DATES. Married people Have AFFAIRS
You're a special kind of stupid. Two single people can have an affair you ignorant twat. Why don't you provide the definition with link that says ONLY married people can have affairs?
You're a special type of tawdry trollop:
Two single people cannot have an affair with each other:
date - Definition from the Merriam-Webster Online Dictionary
3. to date (v) :having active romantic relations between two unmarried people.