Pronoun set
The group of forms that go together: she/her/hers, they/them/theirs.
A pronoun set is the group of forms that belong together: subject, object and possessive. She/her/hers, he/him/his, they/them/theirs, and for neopronouns something like ze/hir/hirs.
People usually state two of the forms because that is enough to work out the rest, which is why introductions say she/her rather than the full list.
Multiple sets are common and generally mean any of them is fine. She/they usually means both work; occasionally it means a preference, and the only way to know is to ask.
Asking is easy and briefly awkward. Assuming is easy and lastingly awkward, and the arithmetic on that is not close.
They are pronouns, not preferred pronouns
The word preferred was well intended and implies the alternative is also acceptable, which is what makes it land badly.
Nobody refers to a preferred name for someone called David. Pronouns work the same way, and dropping the qualifier costs nothing.
Saying it well
Say this
- My pronouns are she/her.
- She/they, either is fine.
- What are your pronouns?
- Ze/hir, if you can manage it.
Not this
- Preferred pronouns
- What are your real pronouns?
- Both? That is confusing
- Can I just use your name instead?
Questions people actually ask
What is a pronoun set?
The group of forms that go together: subject, object and possessive, such as she/her/hers.
Why do people say she/her rather than the full set?
Because two forms are enough to work out the rest.
What does it mean if someone uses two sets?
Usually that either is fine. Occasionally there is a preference, and asking is the way to find out.
Should I say preferred pronouns?
No. Pronouns is enough, and the qualifier implies the alternative is acceptable.