Every single one of them knew from the beginning they did wrong, some due being too young is understandable, but of course self preservation and sometimes playing 'the victim' is more convenient, for them the guilt was light and it's easy to believe everything can be forgiven with an apology 3-4...
In Japanese culture college's Tennis club is infamous for being just for playboys to hook up with recently enrolled girls, usually using drinking parties as an excuse to get them drunk and vulnerable, hence her (former teacher) partner's visible worry, there's an extensive trope about this in...
Maybe the guy was an adult, probably married and had second thoughts about meeting a middle school girl, that's a very common situation in Japan; i'm sure he got to the airport, saw her and said: 'nope, i don't want to go to jail'