He meant that the feelings he and Bella have for each other are so strong that he can't even began to comprehend it. It's stronger than anything, completely unbreakable, nothing can make them stop loving each other, nothing can mask the love, it's just them. But even what I wrote is not even a fraction of how they feel, because as I said, it's to much to comprehend.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.