Wait, what? WHAT? His question just completely floors her. She was not prepared for this.

"Because... I--" Just back the hell up. She's gotta sort through everything to answer this one. Give her a second. "Because I didn't want to dump all my emotional shit on you and freak you out and then you bolt. Didn't think you wanted to hear it." Because she doesn't know what this is half the time. Are they still just friends that fuck? Does this count as a date? Are they actually a thing now? It doesn't really matter to her as long as he still wants to hang out.