It doesn't happen overnight. It's such a gradual process that you hardly see it coming. The first years of school, homework in German or French, friends with names that are difficult to pronounce, jokes that cannot be translated. And one day, without anyone having planned it, the language of the country is no longer just the language of school. It is the language in which your child does the math, the one he uses when he is nervous, the one that comes out when he speaks alone.
For many parents, it happens at a particular time. You are at home, you ask him something normal, and he answers you with a word from here, or with a mixed phrase, or directly in the local language because that word in Spanish did not come out. And you stay quiet for a moment, not knowing very well if what you feel is pride or something like nostalgia. Probably both at once. The integration you've been wanting for years has worked perfectly for him. And precisely because of that, something has changed without anyone choosing it.
Spanish does not disappear. It usually remains as the language of home, of grandparents who call on Sundays, of summer vacations, of the usual series. But it is no longer the language in which your child processes the world. That's yours, where you come from. Yours is another place. And living with that, without dramatizing it but without denying it, is one of the things that nobody tells you about when you decide to emigrate with your family or when you form it here.
The irony is that many Spanish parents have been worried for years about whether their children learn the local language well. And when they do, when they do it completely, when it is no longer an effort but their natural language, a new sensation appears that no one has described to you before.