] The mere habit of learning to love is the thing.... I think Catherine's embarassment was a matter of her inability to answer.

I'll have to beg to differ with you, I'm afraid. If you were a seventeen-year-old girl, and the first love of your life were to say the bolded words to you, (particularly if they were said in the right tone of voice and accompanied by a teasing glance, as I've no doubt they were) you'd blush scarlet, and your heart would be pounding so hard you wouldn't be able to hear whatever else was being said. Just the sound of the word 'love' coming out of his mouth and directed at you, would be enough.