If you dating Lauren and Emma at the same time, then during sex with her in a motel, Emma will see you through the window.
Ok, I tried it, and I don't like this dev's decision at all.
What was the point in adding so many girls to the game, wasting time on them (!), if the player can't hook up with them without breaking up in the future? I mean, it is obvious that the main emphasis of the game is
incest, and the main women in the game are
mom and sis (they are on the title of the game for God's sake, moreover, with a hint of the harem ending), so in the end there will be the same story as now with Emma, tears and crying, etc. Why then he adds new characters (like an aunt a couple of episodes ago), if the only way is to break up with everybody in the future? And why did he add Emma from the begging? Only to break up with her earlier or later? It would be much fair, if the MC had been single from the beginning. And what was the point in adding Lauren and Lisa? I replayed from the beginning and told them the truth about Emma, so they just disappeared from the story AT ALL! The Dev had spent fucking amount of time on the side storyline that just disappears if you are faithful, instead of developing the MAIN (true) storyline.
To sum up, it's ok to date with only one girl. But the player must have a freedom to choose. MC has to be single from the beginning and there should be no obvious love roots like mom and sis. All girls have to be introduced from the begging. It's just stupid when you choose one girl and then after a couple of episodes appears one more love interest. Or there should be a harem option. All the rest is just the waste of developer's and players' time.
P.S. Who knows how to unlock the gallery (memories)?