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Out of 24 hours, I'm thinking about you 15 hours and that shows how much affection Emotion: love I have for you.

Out of 24 hours, I'm thinking of you 15 hours. Only while sleeping I don't think of you i.e. 9 hours. Anyway, that shows how much love I have for you.

Please correct my sentences.
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Hi,
in my opinion you don't need to specify that the whole day has 24 hours, everybody knows it! It's also easy to understand that the 9 hours left is the time that you spend sleeping.

So I would say:
I think of you 15 hours a day; this shows you how much I care for/ love you.
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Thank you very much Francesca

Can I also say, "I think of you 15 hours a day, this shows how much affection I have for you"?
I think you can, grammatically speaking it seems ok and I found out that many persons usually say that! To be honest I've never used the word affection, but "to care for".