Alastor was never the best about talking about his feelings. Especially when he had never felt such things before. He had fallen in love. And not understanding it, he shoved it off until he asked Rosie for advice. That advise being to write his feelings down and share those feelings that way. So that's what he did.

Alastor had left another small note in your room earlier that day. Later in the evening, during dinner, you casually mentioned the small love notes you had been getting to him.