If he simply said this, it would look like he wasn't putting any thought into his words when he said them. He hoped she'd just let it slide, but she had become quite emotional these days, so she had a variety of new reactions she released in his presence.
What was her problem?
Wait, he didn't even need to ask because he already knew.
He was just the one playing the oblivious game so he wouldn't need to start thinking of responsibility so early on. If she just wanted to have fun, then he could go along with it, but he knew that was not what she wanted.
She wanted commitment and time and he wasn't sure he was cut out for something like that.
He wouldn't cheat, that's for sure, since he didn't particularly hold interest in such things, but... What if he couldn't give her what he wanted?
This was the single question that weighed on his mind and he had his fingers dug into his hair a few times trying to think up an answer.