When you arrive in French-speaking Switzerland, it is common to be impressed by the language.
At the beginning, there is a strong motivation to integrate and learn the language and then, faced with the difficulty, demotivation can follow.
Learning a new language is not easy.
Several human and cultural factors are at play:
his level of motivation, which may fluctuate over time,
perseverance and discipline in learning,
his willingness to integrate using French,
its language and culture of origin, which can be very different,
his time available, to study and practice the language,
his time of exposure to French by working mainly with foreigners and travelling a lot.