In Switzerland, an application for divorce, whether mutual or individual, does not necessarily require the exact reasons for the marital breakdown. A joint application need only express both parties' wish to divorce. An individual claim must instead establish two years of separation or that continuing the marriage is unreasonable. Only when unreasonableness is asserted must it be specifically explained why waiting two years is unacceptable. That reason often, but not necessarily, coincides with the main reason for wishing to end the marriage.
In brief: If you apply because of a mutual wish to divorce or after two years of separation rather than unreasonableness, no reason for wishing to divorce is required.