Quentin... You are correct. Sometimes we simply say "so" by itself. "So" can have a similar meaning to 'to that extent' or 'that much' or 'very much'. It is often used when we are talking about a high degree of some quality (like love or hate), and in situations where 'very' is also a suitable word. "I love you so" = I love you so much / I love you very much / That is how much I love you / That is the way (in the manner previously mentioned) I love you.