It started with the shame I felt when I realized that I was almost as creepy and entitled as the people I described in the above post. I say almost, because even though we'd argued over sex so many times, I never took shots at his appearance in order to get revenge because he'd rejected me, or implied that he'd never be enough for me. I never lost respect for him as a human being. I never attempted to manage his health or his diet, or treat him as a child.
But I was definitely hyper focused on his free time. Analyzing everything, trying to jump in any time I felt he couldn't easily say no. Like when the kids were asleep, or before they woke up. Really unfair, to put him on the spot and force his hand. He knew what I was doing. I knew it, too. Creepy as fuck. I hate myself for it. I hated reading how some of the angry HLs treated their spouses as children, and then demanded sex from these children. So gross.
I've never been religious, but when I was a kid I felt like I needed to believe in something so I started with Kant's Categorical Imperative. It says people are ends in themselves, not merely a means to your end. We can't make, wish, expect, or guilt someone into serving our needs. They have the exact same right to peace, happiness, and the freedom to pursue their own goals that we do. It's wrong to impinge on their freedom. I've lived with this consciously on the surface of my brain my whole life, until we stopped having sex and I carelessly forgot it. I take being faithful and a good partner very seriously, so I'm always GGG. I want to be that great partner and build a strong relationship, and since I was, I expected him to have the same interest in keeping me happy. Which is bullshit. I'm only responsible for how I feel, and for my own actions. I have no right to make anyone else do, say, or feel anything just to add value to my life. Who the fuck am I? No body. No one owes me anything, and it's not okay to obligate someone to entertain me.
I did the ultimatum, which was simple me explaining that I couldn't sustain love with someone who felt like my brother, and told him the reason I wanted out.
"Hey, I told you how important sex is to me, and you know I'm really unhappy without it. This is something I will leave you over, unless you decide to meet me halfway and let me know what you need from me so that we can enjoy each other again. Think about it, because even though I love you, I don't want to live with a roomate. I'm already packing."
I didn't tell him what to do. I didn't make any demands, or ask for any particular flavor or frequency of sex. I just told him my truth: I was falling out of love with him and was starting to feel weird about kissing him or even being naked around him because he felt so much like a sibling.
But that isn't what changed. I just started living as if I actually were leaving. Picked up my old hobbies, quit making plans around him and around his plans. Went for a hike whenever I wanted. When to the grocery whenever I felt like it. Took a bath without asking him to keep an eye on the kids. I still hugged him, still asked if he wanted to do family things, still cooked and cleaned and took care of all four of us as I always did, still snuggled up with the family on the couch. Unless I was interacting with him and the kids directly, I simply behaved/pretended he wasn't here.
It wasn't a test. It was something I had to do anyway. Be independent again, drop my fixation on him and my expectations of him. And he came back to me. Not because he was practicing reset sex, but because this me was exactly like the me he fell in love with, instead of that mopey girl hanging around every single minute he was home. When I stopped expecting him to complete me, we started loving one another again. And we're still going strong, months later.
But I really do feel like the only one with the power to change this is my SO...
She won't want to, because somewhere inside her chilly brain she knows you are a grown woman capable of entertaining yourself and she resents the responsibility of keeping you satisfied. Because she doesn't need it as much.
Tell her you will leave her. And start living as though you are alone, except remain kind and considerate. But don't live for her, or around her schedule or habits. Just live as though she isn't in your house, except for those moments when you have plans or are speaking. Just get up and go do abcde things. Live like you are hoping to meet someone new; a better match. Just be sure to tell her that you are on your way out, and that you are unhappy living with a sister. Tell her it's destroying your identity, and that you (abcde) have to get your life back because you don't want to be one half of a sibling relationship.