It's not random, it's a "hidden feature". I completely forgot about this in the change log...
"Decisions matter now! A new system has been added that will make your adventure easier (or not) when meeting a girl.
When you meet a girl, usually several decisions are presented, according to what you decide, when you unlock that girl, extra points will be added to different stats.
For example, depending on what you decide when you meet Anna (be more understanding or be more strict), at the end of the quest, you can have +X extra points in her trust (applied permanently every time you spend time with her).
This works internally and there is no way of knowing, it is up to you to make the right choices.
If you make the "wrong" decisions, you simply won't get those extra benefits.
NOTE: This is a purely RPG system, it does not affect the story or your adventure in any way."