There were a thousand reasons not to kiss her, at least five hundred of which being how many times her father could punch him in one second. By her own admittance, she wouldn't hold a grudge against him if he couldn't handle it. And if he had been Captain Marvel, the wisdom of the ancients would have weighed in and he probably would have flown home, spent a few hours with a certain amount of hand lotion, and eventually found a girl who didn't delight in giving him a heart attack on a semi-daily basis.
Fortunately, he ignored everything that was probably healthy for him and kissed her before she finished the word "ever." "I don't know if there are any magic spells that can protect me against someone who moves faster than sound. But that's what the library's for."