Its true that they were fine with being part of France after a time....though they didn't like the way the government stepped hard on the Catholic church, on Catholic education, etc.
BUT
They were also just fine with being part of Germany again after 1871. You did not see any resistance or protests to it in Elsass-Lothringen. They were perfectly content doing business (Germany was a strongly rising economic power) nor demands for French to be spoken, etc. They thought of themselves as German and seemed perfectly content with that. The only objections/resentments came from France, not the locals.
Hmmm, as far as I know, this did vary from time to time, and from one social group to another.
The intellectuals were mostly a bit of Francophiles, while the farmers, the workers and the artisans were more pro-German. Social security and pensions for invalids came along in the late 1870s and later, and they vere welcomed. More and more, the people of Alsace-Lorraine did arrange themselves, especially after 1911, when Alsace-Lorraine was finally granted autonomy and legal parity with the other German states.
Still, some misunderstandings persisted, as the Zabern affair of 1913 showed. However, it was blown vastly out of proportion by the French media in France.
There had been a turnaround recently before, after, between 1890 and 1905, revanchism in France had died down to some degree.
However, with the Morocco crisis of 1905 and the reassuring through the Entente cordiale with Britain, it intensified again and the French media did their best to pour fuel on the fire. People like Hansi and Zislin, vile caricaturists in service of France, are famous or infamous to this day.
Hansi, who is today mostly known for his mawkish genre postcards, had plenty admirers even in our days. This, however, declined somewhat when it was found out recently that he was not only a Germanophobe, but also a radical antisemite. Some of his early drawings have an uncanny resemblance to similar “art” in decidedly antisemitic papers.