Very Long story, short of it is i violated my own morality and my girlfriends bodily autonomy because her brother is a sociopath.

Then gf and I in a rough patch and nothing is working between us and neither of us knows why. We were great for a year then it all just fell apart and from my POV everything she is doing is making it worse.

Anyways she keeps telling me i need to talk to her brother because "he understands things" relationship-wise and has always helped her. Disclaimer: I do not like her brother, i find him a smug, narcissistic, condescending jerk who is often intentionally hurtful towards her and the rest of his family.

So 8 months of near non-stop fighting im at the end of my rope and i finally relent and talk to him. During this conversation he agrees she is being unreasonable and suggests she is mentally unstable, always has been and does not know why i am with her. Considering what has been happening lately i agree because everything he says lines up and makes sense.

His solution was for him and his gf to talk my gf, his sister, into taking certain over the counter meds to help with mood stabilization and maybe even taking some of his prescription meds. I have issues with this, im not a fan of tricking people into taking drugs, legal or otherwise or not going through an actual doctor for a proper diagnosis. Heres the kicker, and where normally red flags would have gone up everywhere, I cannot be involved in this in any way, im not even suppose to know about it or according to him she will just think it was all my idea and wont do it. As im at the end of my rope and definitely not thinking clearly, i agree to his plan.

That right there was the worst mistake of my life to date

This is already long enough so ill end by saying this, after 3-4 weeks we break up anyways and in the ensuing fight i bring up why shes on the pills and detailed that her own brother agreed.

Many months later we are finally talking again civilly and she asks me to sit down to discuss our relationship. I come to find out while not everything was his doing, a good portion of what had been wrong in our relationship (and her life apparently) was directly from her brothers advice to her. In those talks a lot of times he would tear her down saying things like "what do you think a guy like that (tall, blond, businessman) that sees in someone like you (short, fat, quirky)"....which explained a ton of the jealousy issues we had. He would also go behind her back to her friends/rest of the family to discuss her erratic behavior (most of which was his advice to her) and caused major relationship problems. Its been over a decade and she is still trying to repair many of those relationships.