I think you've said it all. It didn't go with Squall's character to make a statement like that; I know because I can very rarely use those words myself without it sounding really corny. Either it would have been awkward for him to say anything or he would have only hinted at it. For example, when he goes into space to rescue Rinoa, she could have asked him afterward why he risked his life for her, to which he could have said something like "I think you know why." It would have been a way of telling her without saying it.
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