help i can’t remember

i read this a while back it’s straight but all i remember is that in the first couple the girl acts like she’s super innocent around others and her bf but she actually is very dirty minded and is just “dirty” in a sexual way ig umm let’s see if i remember correctly one of her dirty fantasies was like “cheating on her bf” but like not actually like she made up this whole fake dude for her fantasies and im pretty sure in one of the scenes she’s having sex with her bf she says this fake guys name idk i can’t remember all too well.. oh and the second couple i think the girl had short hair and the guy had tattoos PLS HELP