Does a bubble exiting the front private part—without sound or smell—nullify ablution, especially when one is afflicted with obsessive thoughts concerning purity and prayer?

Dismiss these obsessive thoughts and do not rule that something has exited except with absolute certainty. Do not repeat a prayer or ablution except with this certainty. What you feel about a wind from the private parts is a whisper [from Satan], and you can adopt the Maliki view that it does not nullify ablution. A person suffering from obsessive thoughts is permitted to adopt the easiest of the madhhabs (schools of thought).