Meu amigo ficou solteiro de novo, mas diz que está feliz.

In Brazilian Portuguese, both meu amigo and o meu amigo are possible.

• meu amigo = very common, natural, and slightly lighter
• o meu amigo = also correct, a bit more explicit or stylistically fuller

Before possessives like meu, minha, seu, nosso, Brazilian Portuguese often allows the article, but it is not always required. In this sentence, meu amigo sounds completely normal.

Because ficou solteiro means became single or ended up single.

• ficou solteiro = he was not single before, and now he is
• está solteiro = he is single now, without focusing on the change

So ficou highlights a transition in relationship status.

Ficou is the pretérito perfeito of ficar for ele/ela/você.

Here, it means a completed event in the past:

• ele ficou solteiro = he became single

This tense is often used for single, finished actions or changes.

Solteiro agrees with amigo, which is masculine singular.

• masculine singular: solteiro
• feminine singular: solteira
• masculine plural: solteiros
• feminine plural: solteiras

So if the sentence were about a female friend, it would be:

• Minha amiga ficou solteira de novo

Here, de novo means again.

So:

• ficou solteiro de novo = became single again

In everyday Brazilian Portuguese, de novo is extremely common. A more formal alternative is novamente, but de novo is the most natural choice in normal conversation.

Portuguese often drops the subject pronoun when it is clear from context.

So both are possible:

• mas diz que está feliz
• mas ele diz que está feliz

The version without ele is very natural, because the subject is still clearly meu amigo.

Because que introduces the clause reporting what he says.

• diz que está feliz = says that he is happy

In English, that is often optional:

• He says that he is happy
• He says he is happy

In Portuguese, que is normally required in this structure.

Estar is used here because feliz is being presented as a current emotional state.

• está feliz = he is happy right now / at the moment
• é feliz = he is a happy person / he is happy in life in a broader sense

In this sentence, the idea is that despite becoming single again, he says he feels happy now, so está feliz fits better.

Both are in the present tense.

• diz = he says
• está = he is

So the timeline is:

• ficou solteiro = past event
• diz = what he says now
• está feliz = how he says he feels now

Because feliz is one of those adjectives that often has the same form for masculine and feminine in the singular.

• ele está feliz
• ela está feliz

The plural does change:

• eles estão felizes
• elas estão felizes

So in this sentence, feliz stays the same because the subject is singular.

Yes, very common.

Portuguese often uses ficar + adjective/noun-like complement to show a change of state:

• ficar solteiro = become single
• ficar triste = become sad
• ficar doente = become sick
• ficar pronto = become ready / be ready

So ficou solteiro is a very natural way to say someone became single.

Because mas means but and connects two contrasting parts of the sentence.

• Meu amigo ficou solteiro de novo = one idea
• mas diz que está feliz = contrasting idea

Using a comma before mas is standard and natural here, just like before but in many English sentences.