Here is the story from Mark Manson's book, (No copyright intended, posted just for the sake of knowledge) I'm in a situation so similar its uncanny. Not everything is identical, but its pretty damn close. (Even the names and specifics are pretty similar O_o)

Daniel is 24-years-old and trying to get over a three year dry-spell. It’s the first time he’s pursued women since his only girlfriend dumped him three year ago.

Daniel goes out to a bar one night and approaches Stacy. Daniel approaches her with what seems like an innocuous question about drunk guys getting in fights. She responds and he follows it up with a number of quirky lines to soon get her laughing.

These are lines and questions Daniel learned from reading a book on women. Daniel has been practicing the tactics for a while and has recently become proficient at using them. After facing countless rejections, he’s finally able to get girls’ phone numbers and even a few dates.

He continues to talk to Stacy throughout a lot of the night about preordained topics he’s comfortable with. He’s able to punctuate each lull with tried and tested jokes he’s used dozens of times. Every time, Stacy laughs on cue. He puts his arm around her and she leans into him.

A week later, after some fun texting, Stacy meets up with Daniel for a date. Once again, Daniel executes everything he’s learned: stick to topics about her passions, move her from venue to venue, never sit across from her but next to her, use a planned excuse to get her back to his place, etc.

There are hiccups along the way, but it all more or less works. Stacy seems genuinely attracted and when Daniel finally works up the nerve to kiss her, she kisses back enthusiastically.

Daniel is ecstatic. He feels like the months of hard work has finally paid off.

The second date goes similarly. Daniel manages to get Stacy back to his apartment where fumbling through his excitement, he has sex with her.

Daniel is on cloud nine, delirious with excitement, he jumps online to his favorite pick up forums and writes up a post detailing how his tactics and lines worked and how everyone else should use them. [This didn't happen] Little does Daniel realize that it wasn’t his lines and tricks that Stacy fell for, it was the endearing way he laughed at himself whenever he was self-conscious. She thought it was cute and it reminded her of her first boyfriend. She decided Daniel probably hadn’t been with a girl in a while and she wanted to feel needed by someone, so she decided to help him with that.

Daniel continues to go out and run his "game" but he’s always excited to see Stacy again. They see each other a few more times over the ensuing weeks, but something changes. Since he’s already had sex with her, Daniel stops running his lines and tactics that he learned. He slowly reverts back to his normal self. His needy self.

[I'm right here right now.]

It begins subtly with him agreeing with everything she says, followed by a sudden inability to come up with new and interesting topics of conversation. What used to be vibrant and hilarious bantering has now turned into Stacy showing up, saying whatever she wants and Daniel more or less agreeing with her until it’s time to have sex, really bad sex.

One day, Daniel texts Stacy about meeting up with him that weekend. She was busy studying for a test that night and didn’t reply. Daniel begins to get very insecure about why she’s not responding. He gets on a message board and makes a post about it. The next day, there are numerous replies with all sorts of "antiflake" strategies and possible reasons that she’s not talking to him anymore.

[Doesn't this sound familiar...]

He decides to text her some of these "anti-flake" texts that involve some silly lines and a playful tease. Again, she doesn’t respond. Daniel gets even more upset.

The next day, after her test, Stacy sees her phone and notices four new texts from Daniel. The first one is casual, but each one gets progressively weirder and nonsensical. Stacy is turned off, but willing to overlook it and replies that she was busy taking a test but could see Daniel that weekend.

But Daniel is not so easily fooled. He’s not about to reward Stacy’s "shit test" by immediately hanging out with her. He’s read theories on punishing women for "bad behavior." So he waits a few hours and then texts Stacy that she’s too late and he’s already made other plans with other people. She finds this strange and is annoyed since he had texted her four times, but shrugs it off and goes on with her life.

Two days later Daniel texts her again insinuating that he’s ready to see her now. The condescending and disrespectful tone pisses Stacy off and she doesn’t respond.

Two days later Daniel, drunk and confused on why she doesn’t want to see him anymore, sends a sappy text saying that he really likes her and really wants to see her again and doesn’t know why she doesn’t like him anymore.

Completely confused and turned off, Stacy replies that he’s a nice guy but she just wants to be friends even though she has no intention of ever seeing him again.

I can tell you that I’ve seen both of these stories play out over and over and over again, in hundreds of different forms between hundreds of different people.

Guy meets girl. Guy shows less investment than girl (or induces more investment in girl), sex and/or relationship occurs, guy becomes more invested than girl, sex stops and/or relationship falls apart.

The first story is an example of why it’s important to lower one’s neediness by investing in himself rather than the woman he’s with. It’s the only long-term solution available to keep long-term relationships stable and happy.

Okay, I have set the stage. I'm sure there are others in this situation, but how does one fix this and prevent this from playing out literally word for word?

One idea I had was to just go full stop and break up and send this off the rails so the second part doesn't become true.

The fact that I even made this post is probably just proving any neediness I have and therefore progressing the story... So meta...."The next day, there are numerous replies with all sorts of "antiflake" strategies and possible reasons that she’s not talking to him anymore.