>>2342338Lilly's family is practically completely estranged from her since she grew up separate from them. It's even established early in the route how she barely feels comfortable going to see them. Her friends in Japan are much more of a family to her than her actual family.
Despite being still young, they have clear ideas of what they're doing for the future, the jobs they're going for. It's well established that they're not just some dumb teenagers, too.
>stupid decisionMore stupid than going back forever to a family you don't know, leaving all you've ever loved to work in the family business you don't want to go to abandoning all your dreams for the future and the person you love?
>Boyfriends are largely temporaryIf it being a romance VN didn't cue you in, it's not meant to be the average scenario. Even the ending pretty much establishes that they're together all their life through all the challenges ahead. The relationship is by far made out to be not just some boyfriend-girlfriend lovey-dovey thing. It's just short of a flash-forward to a wedding and adult epilogue. Again, romance story. If those things weren't to work out there wouldn't be a story. Also, pretty much everyone in the VN is better off and happier at the end of Lilly's good end.