Feeling Lost
To encourage his daughter to be more sociable, Dale wanted to talk to her. He yet wished to appreciate her individuality and freedom. It made the most sense to leave her alone for the time being as she might just be going through a phase.
Letting Her Be
He also wanted to give Lise her freedom and independence, though, as she appeared to value both. He wanted to give her the freedom to make her own choices and errors. Hence, he made the decision to leave her alone and not disturb her about it.