Well some I can and some I cannot answer in full ^^
Some I can't answer because they aren't defined nor planned that detailed into future.
What I can say is that there are currently 2 "clear" decline like choices (one you probably encountered) and the game does remember that. I didn't want it to instantly close routes, kinda going by the real life implications that if a girl might like you that she won't instantly lose interest. Naturally that doesn't mean that each girls route can survive such choices (or same amount). For example maybe if you deny someone in future it would hurt the girl more and add instantly 3 points, instantly closing her route, but if you decline/do something else related to her that might only add 1 point into losing her route, if my explanation makes sense.
And for total points/% that part I haven't fully decided yet. At the moment (there are some adjustments I'll be doing in my next planned update) if you lets say dont have a certain threshold of points in some places, you simply don't get the "better" choices/outcomes and get the worse/worst ones. That also makes you lose even more points as there are many instances of "if idk Raiko >=15 and you do X choice, get += Raiko extra point".
I'll have to decide in future where I'll draw the lines with total points, and at which point the points themselves (and not the above declining choices points) would close routes.