Spanish Reflexive Pronoun Se with Unplanned Occurrences
The reflexive construction, used mainly with pronominal verbs, can
also be used to describe accidental and unplanned occurrences.
Se me olvidó el libro.
I forgot the book.
Se le cayó la pluma.
He dropped the pen.
In this type of construction, the reflexive pronoun se
indirect object pronoun that indicates the subject, and the
verb, rather than being conjugated to agree with the subject, agrees
with whatever noun follows the verb.
Se me olvidaron los libros.
I forgot the books.
¿Se te perdieron las llaves?
Did you lose the keys?
Sí, se me cayeron ayer.
Yes, I dropped them yesterday.
The accidental reflexive construction indicates that the action was
unintentional. In addition, because the subject is only referred to by
an indirect object pronoun, this construction gives the sense that the
subject is not to blame - he or she had nothing to do with the accident.