Just a guess here, but it sounds as if you are using the point system as the only variable to set scene triggers. And if someone uses the cheat there will be two scenes available but only the latter scene will show.Actually, I have been seeing these a lot too and have been thinking about this.
The problem is that each event has as a set of conditions that can be very complex and the events are not (really) linear.
So that means that it's hard for the game to "know" which event is next, except by looking at the current stats,
(this is how the new hints system works as well).
So when players max their stats, the lower and upper limit of an event condition gets exceeded and they won't trigger anymore.
The only real solution I see would be disabling the stat cheat altogether (which would not really be a good solution either).
So I got some more thinking to do...
I hope so, I think it will make it a lot harder to get stuck and hopefully you won't need a walkthrough anymore at all.
However raising the stats too high, would still be problem.
Actually now that I think about it, one solution would be to cap the stat raise cheat to the event that matches the number of stars (however this would be a lot of work to implement).
It would be much better to use those stars as a second cross check condition to trigger events.
So if Event A requires 40 and Event B requires 45, Event B would also require the star from Event A.
The logic would be something like this....
If Points >40 and Star A = 0 - Display Event A, Star A = 1
If Points >45 and Star A = 1 then Event B Star B = 1
By doing that you are requiring users to complete all events meant to display before the event they have the points to see now. Basically two conditions. One to see that the relationship is high enough and the second (stars) to see if you have completed all the other scenes that should precede that scene before you can get it.
If you did that, even if a cheater maxed out the relationship stats for all the women they would still see every event in the proper order they were meant to be seen in.
It will be a lot of work I suspect to go back on all previous events and set that second conditional (adding a flag to each event that you can check for on the next event) but it would be a much safer and bug free method of pacing and ordering the action the way you intended.
In fact you should already have a list to cross check with that is used to display all the Milestones and stars you have completed in the game. So it is just a matter of checking that table and making sure event A is complete before Event B can display even if the relationship point variable says you have the points to see it.