fiction - How to deal with a story that 95% of it takes place in a different language country and the protagonist speaks in it?

The protagonist is from a certain country, and in some point of the story he moves to another one that speaks another language. The protagonist learns their language and talks with them in it.

Movies (usually North American ones) set in another country, almost always have one or some characters who speak English, lowering the impact that the foreign language causes. However, the fiction I'm writing is quite long, and I think that only 2 or 3 characters who speak the protagonist's language throughout the whole story is quite inadequate.

Some parts of these movies have dialogs in the local language, but with subtitles. What about a written story? Provide the translation right after? That would be partially good only if these parts are few if compared to the whole story's dialogs, but that's not my case.

Also, fictions set in another country, but that don't have a change in the local language, are much easier than those that do have, because if, for example, the story is an adaptation from a Chinese story, anyone would know that though every character is speaking English, they would actually be speaking in the local language.

But would this be possibly applicable to the situation when there's a country switch? All dialogs in the other country will be in the same language as the ones in the initial country? Wouldn't it be weird or unrealistic?

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EDIT:
Sorry, I think I didn't explained much clearly. I explain:
The problem is the language in the dialogs, not the narration. This story involves a lot of dialogs, and the protagonist moves to another country and learns their language. The problem with this moving is the change in the language in the dialogs, that, in reality, would be another one. And my question is how to deal with this situation in the story.

Answer

We have four variants of foreign language dialog in fiction and the corresponding solutions how we can handle this:

+----------------------+-----------------------+-----------------------+
|                      |    foreign language   |    foreign language   |
|                      |     is limited to     |    makes up a major   |
|                      |    short phrases or   |   part of all dialog  |

|                      |   occurs only rarely  |                       |
+----------------------+-----------------------+-----------------------+
|      the protagonist | translate the phrase; | translate (2)         |
|      understands the | use typography (1)    |                       |
|     foreign language | to signify foreign    |                       |
|                      | language              |                       |
+----------------------+-----------------------+-----------------------+
|      the protagonist | give the original     | describe that people  |
|  does not understand |                       | speak ('Tik said      |
| the foreign language |                       | something and pointed |

|                      |                       | at the sky.')         |
+----------------------+-----------------------+-----------------------+

Notes:

(1) Signifying translation typographically is optional. Usually the context makes it clear enough that if an American goes shopping in France, the clerk will speak French. Readers use their knowledge of the world to supplement the texts they read.

If it can reasonably be assumed that the foreign person speaks the protagonist's mother tongue, typography can help make the difference clear. Explain the convention the first time you use it. E.g.:

Bob and his wife flew to France. When they arrived in Paris, the customs officer said to them in French: "Please show me your passports."
"What did he say?" Bob's wife asked.
"He wants to see our passports," Bob answered and handed the passports to the officer.

"Thank you," the officer said.

What conventions you use will depend on your book design and your publisher. I have seen the use of italics, as in the previous example, and angle brackets:

〈Please show me your passport,〉 the officer said.

Do not use markup or typography if foreign language dialogue is extensive (as in your book). In that case, just translate it and let the context make it clear which language is spoken.

(2) Wether or not you translate foreign language dialog will depend on your readership. If you write for a highly educated audience, it is quite common to leave French or Spanish text untranslated in English fiction. But if you write for a more general audience, you should aim for a monolingual text. The exception is fantasy and SF, where Elvish and other fictional languages are often left in the "original" for effect.