Hello, definitely an IRL yandere here. I didn't realize it until I fell in love again recently. Before this relationship I was single for 4 yearsish. While I have no diagnosis, I suspect I suffer from OLD (Obsessive Love Disorder). I get violent thoughts at the idea of my SO just being around other people. I yell, I get angry, not good stuff.
I've started to notice I require her attention often, at least an hour a day, just to stay healthy. I have self-isolated myself and tend to avoid people besides my SO, going as far as to remove 90% of my friends. My entire world revolves around her and only her. From my waking to my dreams, she is often the only thing on my mind, I get sick when she isn't around.
I'm entirely not a good person, but I am extremely lucky to have found someone who accepts me despite my horrible behavior. She knows my darkest parts and we have had discussions about it. She finds my obsession "cute" and "addicting" which is a massive bonus to me since I am normally called a creep and get blocked when I make advances towards people.
Being a yandere isn't fun, in all honesty, but I've come to accept myself, this is just how I am, and I am super happy to be in a relationship where I am loved and appreciated, and not only fetishized for my die hard obsessive and possessive behavior.
I know I left tons of details out so ask me anything if you have any questions for me.