Does divorce take effect with the statement "we are not destined for each other" (meaning we are not destined to be together in marital life), especially with the intention of divorce, and with prior obsessive thoughts about divorce and a desire to end the relationship?

A divorce issued due to obsessive thoughts is not effective, whether it is explicit or implicit. If there is doubt about its occurrence, whether due to obsessive thoughts or free will, it does not take effect. Therefore, your divorce, as you described, does not take effect unless you uttered the phrase intending to effectuate the divorce, of your own free will, and fully aware of what you were saying. For a person afflicted by obsessive thoughts to initiate divorce to rid themselves of these thoughts is a misguided approach, as Satan wishes to cause separation between a person and their spouse. The cure for obsessive thoughts is to seek refuge with Allah from the accursed Satan. It is advisable to present the matter to trustworthy scholars in your country and to completely ignore these obsessive thoughts.