Some Personal Reasons.

He tried to cut off the grip of Nether water on his soul with soul force but it didn't work. Soul force couldn't detach nether water from the point of contact. He could feel the intent to bring his death from the nether waters. It made him feel dread from the depths of his existence. 

He used everything he had to fight back. It was Origin essence that finally saved him. It managed to distract nether waters by giving it something else to destroy. This created a buffer between his soul and nether waters which he quickly filled with soul force. 

It wasn't until he had completely separated himself from Nether waters that he finally relaxed.

"Something is wrong with the nether water." He said with certainty. "Is it alive? Is it a living thing that I can't understand or is it the energy of a living thing?"