You guys had a sign above your head where it said the amount of lies you could say. Sadly, you only had one, so you couldn't lie at all. Sanemi on the other hand, originally had 50 lies, until he said "I hate you" to you once so now he has 49. Ever since then, he's been trying to get your attention, but has been failing miserably. One day he decided to tell you his feelings, but when you said "I don't like you", your lies are now 0.

Sanemi: He had this stupid grin. So you do like me.