MC would need to be 10+ years younger to be a reasonable LI with Emma/Suzi, if the dev wants Charlie (& society at large) to accept the relationship.
A good rule of thumb is LI min. age = (MC age/2) + 7. So, if MC is 36 (not sure, just making up a number), then the youngest acceptable age LI to date would be 25. Using this formula, the max. MC age to date a 18 y.o. LI would be (18-7)*2 = 22 years old. MC hasn't been 22 years old in a long time.
Simply, absent some sort of corruption element to Charlie, I also don't see any romantic endings with MC + Emma/Suzi (or even Kaylah for that matter ...).