I did this to someone once. I told her I didn't want to get married, the relationship lasted 4 years...I left the country, and I kept a cold distance from her emotionally. She was a great girlfriend, great wife material, but after a while, I realized that she was manipulating me and she had a crazy jealous side to her that abhorred, I had completely lost interest in her, I wasn't attracted to her emotionally or physically at that point, and I had to find a way out without ruining her (I think I did more damage by this method in hindsight). I did it a terrible way, but the only way I knew how...like a pussy that doesn't give her respect, and this led her down a dark hole that I have heard she has been spiraling down ever since (about 4 years now).
As I said briefly earlier, I left the country for work, and she tried her best to keep it going...I played it in just a way to force her to give me an ultimatum (which I knew she would), and I said "I can't...I'm not getting married"...when what I really meant was "I'm not going to get married...to you.". I married my next girlfriend, and she believed that I had planned this out all along...when I didnt.. I tried to be cautious about it and not really post it on social media (there really is nothing secret on the internet) because I really didn't want to hurt her more, because while we were together she was amazing and helped me through the absolute hardest time in my life and I will always be grateful to her (did I mention I was an asshole) but she cybersleuthed it all and figured it all out by figuring out who I was dating (not on anything public) and she then stole a bunch of my stuff like my camping equipment and my beautiful plasma TV that I still miss today..as well as some skiing equipment and my vacuum of all things (these were in a storage unit that she owned and let me use...so yeah...I'm lucky to have gotten anything back).
Anyways...I know she has friends that are redditors, and if they see this, let her know I'm sorry for doing it the way I did, and she technically did nothing wrong and just needs to find a guy that appreciates her for all she has to offer..that guy wouldn't have been me...I just didn't want to live like that anymore...I needed more freedom and to be less controlled by her jealousy and not letting me have any of my old friends except for my best friend...the only one she didn't push away.