The age difference is huge, but it's a very sweet story so far. I really like that meeting Asahikawa helps him reconnect with his daughter. That she can easily see that they are in love. That he doesn't hesitate to go out with him even if he isn't sure about his feelings.
Do mind the age difference, this is a man with a daughter of seventeen dating a guy in college. I normally hate this but this is done almost perfectly. (Although I wish their age gap was less extreme)