Simple request but maybe a little hard to find, I'm looking for 18+ series (or one-shots) in which the girl discovers or is told that the man (or maybe woman) she fell for seduced her through a deliberate deception, and decides to do something about it. The deception could be a broad range of things. It could be as simple as her realizing that the guy had been stringing her along and really was just using her for sex or money. Or it could be something like the hentai anime Kite from way-back-when, where the heroine's parents were killed when she was about 12 and a cop took her in, training her to be both an assassin and his personal sex slave while swearing to her that he'll get her parents' killer, which by the end she's revealed to have long since realized was actually him; once she's ready, she deals with the situation according to her own particular hard-learned skills. Or it could be something like a guy realizes two people are in love with each other, encourages the girl to believe it's actually unrequited, then comfort her to show off how "gentle" and "kind" he is (note, in this case if the original love doesn't get her back forget it). Whatever the case the core is the same: a man tricks a girl and uses his deception to seduce her, making her his until the day she realizes that she's been had and decides to do something about it. Extra points if her response goes beyond merely leaving the bastard.
Sorry to say I don't know any examples off the top of my head. The best I have is a one-shot where I found myself thinking that the girl had to be either a complete idiot not to realize she was being deceived or a horrible girl to not care. It's a one-shot by Itou Ei, don't remember the particular work. The girl loved a boy in her class but feared that her love was unrequited. The boy's father "comforted" her, and she wound up falling for him and later marrying him. A couple years later when the bitter boy who'd actually always loved her comes home and she accidentally reveals her former crush, he goes crazy and does things he very much regrets before revealing to her that he'd always been in love with her. The way it's done, it'd be obvious that the father knew about his son's feelings, so the girl should have realized immediately upon hearing this that her husband had, rather than help her get together with her love and support his son, chosen to use and encourage her insecurity so that she'd become his. Even if she didn't turn to the son after what'd happened, the fact that she jumped into her husband's arms when he got home leaves me thinking that she's either too dumb to put two and two together or cold enough not to care that she was married to someone who'd lie to her and let her think her dreams wouldn't come true for his own benefit.
The next closest thing I can think of was a one-shot, and a loli one at that, by Maka Fushigi. A girl had been forcing her best friend to mess around with her for years, only to one day declare that they were never doing it again because she'd just become the girlfriend of the hottest guy in the school, then goes on about how awesome he is and how kind before leaving. Then one day he takes her to his apartment which he apparently uses like a brothel, then drugs her so that she'd be unable to resist as two older men raped her. He may not have "deceived" her in the sense of actually lying to her, but he'd most certainly kept things from her for his own benefit and been using her. She doesn't do anything personally though. All she does is run to her friend, who then attacks the boyfriend. The cops catch the boyfriend beating him up and find drugs on him, thus getting rid of him permanently.