I hear ya Anna. I oftentimes dream of being alone again for the mental peace. Bottom line for me though, is my husband is my rock and I'm content with our life. So, instead of running away, which I am prone to do just by my nature, I try to break things into manageable pieces. Like, I find the stepkids too draining to be around during the summer when they're free to run around all hours of the day and night. So I said I won't take care of them nights that H works. Saved my sanity and kept my marriage together. I find that stepping back like that, giving myself space from something that upsets me, allows me more clarity and room so that I don't freak out.
Maybe you could try to get space from your partner? First determine how much space you need. Do you really want to be alone or just have some time by yourself? Once you now how much aloneness you want, you can get your partner to give you what you need. If you need to be totally alone, like forever, and have them move out, then you should work toward that goal. Just be sure that's the goal you want and not just to have some time during the day where you're partner-free. I thought I wanted to be partner-free but upon reflection, it turns out I just need less pressure from him and the stepkids, so having him working opposite shifts from me helps alot. That and not being constantly responsible for the stepkids.
Figure out what you want and ask for it. :)