No, not inevitable. Much harder to avoid after WWII, but even then could have been forestalled by the Cabinet Mission Plan of 1946, though it's an open question whether that plan would ultimately have survived.
No WWII could well result in no partition, as the Congress' boycott of government in opposition to the war, as well as their imprisonment, dramatically raised the profile of the Muslim League. Absent WWII, Britain would also have held onto India some years longer, and with Jinnah's death in 1948, the movement may well have dissipated.
You could also have had the Congress in the United Provinces agree to a coalition with the Muslim League after 1937, as the League had requested. You could have a Liberal or Labour government grant India dominion status in the 1930s, before the Partition movement really picked up steam. Or you could have Jinnah decide against returning from London in the mid-1930s. Or you could have the Khilafat/Noncooperation movement of the 1920s - a combined Hindu/Muslim nationalist agitation - continue, instead of ending acrimoniously.
On the ground, there was no real communal violence or serious tension before 1946 or so. There was a divide between the Hindu and Muslim political elites, but the bulk of Muslim politicians were pushing for power-sharing or at best a confederation, not a full-scale partition, given that most of the Muslim League leaders were landowners in areas that were Hindu majority.