Not surprised she's upset, but I thought the series was going to take a darker turn with the shitty guy she had dinner with, so maybe this'll be a different twist
@ImperiumZero
it certainly isn't REQUIRED to move on, but a lot of people feel like without someone to form new memories with, it's easy to get trapped in the past. which, it sounds like, is exactly what happened with dad.
@Hitspark
If you're looking for something 'off' about kouhai, you could go for the age difference, I guess? He's about 15-20 years older than her, if i understand right.
The whole point is she's (as far as we know) a genuinely nice person who genuinely likes dad.