Shinji's fairly certain that, actually, what he did was more selfish than that, but he also kind of doesn't want to dominate the conversation with how much of a screw up he feels like right now. Let's continue, then.

"Did she give you any idea of what's been bothering her...?" If not, he's more than willing to let the matter lie, there's no reason for him to chase it down again if it's just going to blow up in his face once more, but the part of him that was worried enough to try in the first place really, really wants to know.