Godzilla: The Planet Eater Ending Explained (Spoilers)
After a certain point, it is accepted by most that there is no defeating Godzilla. With the ship in space destroyed by the Exif and the lack of technology on Earth, it seemed integration was the only means of survival. However, Dr. Martin continued to tinker with that fighting suit and revealed to Haruo he got it working again. With that in mind, and the suit able to replicate itself, so comes memories of Metphies saying how all beings create an endless cycle which leads to the birth of Godzilla, destruction of civilization, and eventually whole planets.
So, despite having a baby on the way, Haruo decides to, with Yuko’s comatose body, fly straight towards Godzilla and destroy the only viable piece of technology on the planet. Thus making Godzilla something the people of Earth, as they have done for centuries, something to live with and work around vs. fight head-on.