It's not hard to guess when that's how she's felt in that position in the past. It'd led her to doing her first major spell, re-ensouling a vampire while stuck in a hospital bed, unable to take no for an answer. She hated feeling useless with a passion, and his response is not only hard to take when she genuinely likes him and has been doing her best to be supportive, it's underlining her inability to do anything. She can't even make him feel better.

"But I--" Willow closes her mouth, then gets to her feet before opening it again, expression drawn. "... I'll come check on you later." He's not the first person to just draw into himself when something happened, and she tries with all her might not to take it personally. Xander and Buffy have said worse to her, and they were still close. Would be close, if they were here.

She turns to go, the stark white of the hospital room contrasting the flat tone of her voice floating up behind her. "I didn't mean to make anything worse."