Learn Portuguese (Portugal): Eles iam dormir, mas distraíram-se na rede social. - They were going to sleep, but they got distracted on the social network.

The Imperfeito (iam) sets up an ongoing past intention—something they were going to do. The Perfeito (distraíram-se) is used for the sudden, completed action that interrupted this plan. Using ir (in the Imperfeito) + infinitive, followed by a contrasting action in the Perfeito, is the standard way to express an unfulfilled past intention.

Why is there a -se attached to distraíram?

In Portuguese, the verb distrair means to distract someone else. If you want to say someone got distracted (meaning they distracted themselves), you must use it as a reflexive verb: distrair-se. Without the -se, the sentence would sound incomplete.

Could we place the pronoun before the verb, like se distraíram?

In European Portuguese, pronouns usually attach to the end of the verb with a hyphen (distraíram-se) unless a specific trigger word pulls them to the front. The conjunction mas (but) does not trigger this pull, so the pronoun stays attached to the end.

Why do we use na (in the) instead of a word for on?