Responses
Maybe it is not an indicator of his feelings but the progress of their relationship. He didn't like her so it was negative, he became close to her so it went up. After he realised his feelings it became neutral ground or zero. I don't think it will rise unless she figures out her own feelings or they start a relationship.
I like it, But the only thing I don't get is why the affection meter isn't going up he clearly loves her.