Maybe for dialogue options that iniate sexy content it has a different color text box or some indicator that lets the player know it would be a good idea to make a separate save. Maybe a few pages of the save menu dedicated to making a player-made gallery.
I'm not sure if there are right and wrong choices in LomL.
I mean, you can not have a sexual encounter with a character by not interacting with them or just plainly tell them "no thanks" when it comes up, but there's no puzzlebox characters where you sort of have to get them the yellow flowers because they told you they like yellow 40 minutes ago and if you don't they don't put out.
In fact, in some places, there's some special dialog that triggers if you did really poorly before and lets you make up for that if you want to so you don't miss out. Really, you can't go wrong, and with the "i never want to go off the M+D path" setting turned on (it asks start of chapter 2 or 3 or so, it's a bit of a haze
), so you can even play reluctant straight-laced caretaker mc to the hilt and still have your cake, without a chance of going off the rails.
Saves for your favorite scenes are really the best way to go about it if you want dialog in. The save menu in Renpy is pretty much infinite for all intents and purposes, you can reserve however many pages you want for a gallery.