SPOILER
It was shown in a previous chapter how the king was afraid of his son's disinterest in everything. Royal family history is that occasionally there will be a member that is a genius in all things but will be apathetic to everything. Unless they find an interest in something/someone that will be their focus/obsession. If they don't find a focus, they will self-destruct in a nuke like fashion. These people are called wither great sage or great devil.
I see but huis obsessief with tia, so it should be preventief right?
Yep. The thing that Tia is worried about in the game is that the Prince was fascinated by heroine when she is on his route. If she doesn't choose him, he goes and makes war between countries or something of that magnitude in boredom.
Imagine being so bored with everything in your life you go to war just for something interesting to happen
You know i have read a lot in the comtent that tia reacts to this because of the feature. But what is the bad hing that would happen, Paz spoiler me(づ￣ ³￣)づ