Does a divorce take effect if I made someone believe that the topic of ending the marital relationship is what I am researching, while I was actually researching another topic, out of fear of them finding out what I am researching?

What has been mentioned are mere whispers (waswās) that have no consequence. Therefore, the questioner should not preoccupy himself with these obsessions and should turn away from these whispers. He should beware of persisting in them. Among the aids to getting rid of them are seeking help from Allah, sincerely resorting to Him, and supplicating frequently.