O namorado e a namorada decidiram separar-se, mas continuam amigos.

• namorado = boyfriend (masculine form)
• namorada = girlfriend (feminine form)

Portuguese nouns normally have grammatical gender, so you also mark that in the article:

• o namorado = the boyfriend (masculine singular)
• a namorada = the girlfriend (feminine singular)

The definite articles o / a are used here because we are talking about specific people that both speaker and listener can identify (the particular couple in question), so o / a fits better than um / uma (a boyfriend/girlfriend, non‑specific).

Grammatically, both orders are correct:

• O namorado e a namorada…
• A namorada e o namorado…

There is no strict grammar rule that masculine must come first. In practice:

• Many speakers tend to say the masculine first by habit: o pai e a mãe, o marido e a mulher, etc.
• But reversing the order sounds completely natural too, especially if you want to emphasize the second person mentioned (for example, in storytelling).

So you are free to switch the order; meaning and correctness do not change.

Decidiram is:

• verb: decidir (to decide)
• tense: pretérito perfeito (simple past)
• person/number: 3rd person plural (they)

Rough pattern for regular ‑ir verbs in the pretérito perfeito:

• eu decidi
• tu decidiste
• ele / ela decidiu
• nós decidimos
• vocês / eles / elas decidiram

So decidiram = they decided. It agrees with the plural subject o namorado e a namorada.

After verbs like decidir, Portuguese normally uses an infinitive (not a fully conjugated verb):

• decidiram separar-se = they decided to separate / to break up

If you said decidiram se separaram, you would be mixing structures:

• decidiram (they decided) + se separaram (they broke up)
  That would sound wrong in this context, because decidir needs an action in the infinitive: decidir fazer, decidir sair, decidir separar-se.

So:

• correct: decidiram separar-se
• incorrect in this meaning: decidiram se separaram

‑se is a reflexive clitic pronoun. It shows that the subject does the action to themselves/each other. Here, separar-se means:

• separar-se = to separate (from each other) → to break up

In European Portuguese:

• With an infinitive, the clitic normally attaches to the end: separar-se, ver-se, amar-se.
• Hence the hyphen: verb in infinitive + ‑se.

In Brazilian Portuguese, before an infinitive, you also often see se separar (without hyphen), especially in colloquial speech, but in European Portuguese separar-se is the standard written form.

Both forms exist in Portuguese, but they’re used differently:

1. decidiram separar-se

   • Normal choice when the subject of both verbs is the same (they decided to separate).
   • Very common and completely natural.

2. decidiram separarem-se

   • Uses the infinitivo pessoal (personal infinitive).
   • This is acceptable when you want to emphasize the specific subject, or when there could be ambiguity about who is doing the action.
   • In this sentence, it’s grammatically possible but feels heavier / more formal and is less common than decidiram separar-se.

In everyday European Portuguese, decidiram separar-se is the preferred version.

mas means but (a contrastive conjunction):

• …decidiram separar-se, mas continuam amigos.
  → they decided to break up, but they remain friends.

The comma before mas is standard in Portuguese because mas is joining two independent clauses with a clear contrast:

• clause 1: O namorado e a namorada decidiram separar-se
• clause 2: (Eles) continuam amigos

So the structure …, mas … is directly parallel to English …, but … with a comma.

All of these are possible, but they differ slightly:

• continuam amigos

  • Most natural here.
  • continuar
    • noun/adjective works like “to remain / to stay”:
      
      • continuam amigos = they remain friends / they are still friends.

• continuam a ser amigos

  • Literally “they continue to be friends”.
  • Also correct; a bit more explicit, sometimes slightly heavier in style.

• continuam como amigos

  • Literally “they continue as friends”.
  • Emphasizes the role or status (as friends, not as a couple). Possible, but in this exact sentence it feels less idiomatic than continuam amigos.

So continuar + predicative noun/adjective (like amigos, juntos, casados) is a very common and natural pattern.

Portuguese agreement rules say:

• If the group is all female → feminine plural: amigas, as professoras, elas.
• If the group includes at least one male → masculine plural is used by default: amigos, os professores, eles.

Here, the group o namorado e a namorada includes a man and a woman, so the plural form amigos (masculine plural) is required, even though there is also a woman in the group.

namorado / namorada normally refers to a romantic partner, broadly equivalent to English boyfriend/girlfriend:

• It can be used for teenage relationships, adult relationships, long‑term partners, etc.
• It does not by itself imply engagement or marriage.

For a fiancé/fiancée, Portuguese uses:

• noivo (male) / noiva (female)

So:

• namorado / namorada ≈ boyfriend/girlfriend
• noivo / noiva ≈ fiancé/fiancée

In Portuguese, the pretérito perfeito simples (decidiram) is the normal way to describe a single, completed action in the past, even if it is quite recent:

• decidiram = they decided (once, at some point in the past)

The form têm decidido is the pretérito perfeito composto, and in Portuguese it usually implies repeated actions over time:

• têm decidido separar-se would suggest they have repeatedly been deciding to split up (and maybe changing their minds), which is not the intended meaning.

So for a one‑time decision with ongoing consequences, decidiram is the natural choice.

separar-se has a general meaning “to separate oneself / to become separated”, and in context it can mean:

• For couples: separar-se = to separate / to break up
• For married couples: also “to separate” legally (sometimes before divorce)
• In other contexts:
  
  • As crianças separaram-se do grupo. = The children separated from the group.

In this particular sentence, because the subjects are o namorado e a namorada, separar-se naturally takes the idiomatic sense “to break up as a couple”.