Thor wishes he could make Tony understand why he feels this way -- that after losing so much, he couldn't stand to lose anything else, least of all him.

"If you come with me, there's a good chance you're going to die." As much as he sometimes seems it, Thor isn't an idiot, and he knows Tony isn't, either. He knows there's a good chance he's going to die, but he's ready to go forward with it anyway.