Completely alone? I'm not sure if my situation fits the definition 100% but my effective day to day existence feels like I am.
My dad died over twenty years ago. My mom, I've never had a healthy relationship with, and it became extremely toxic in the aftermath of bullying in college which thoroughly destroyed my life. My mom now has problems with memory loss, and the experience is basically like her life and the person I've known her as is slowly fading. My brother these days is way too busy with his life to have time to talk to me at all, and we haven't gotten along very well.
I have no relatives I talk to anymore thanks mostly to bitter grudges and infighting on both sides, which led to my immediate family being cut out and excluded. At this point, all my grandparents and most of my aunts and uncles are dead. There was an aunt I was close with during my time in college, but the bullying I suffered then destroyed my relationship with her too. She died a few years ago and I never even found out she was sick until six months after her death, as she hated my mom that much and swore everyone to secrecy to keep us out of the loop.
I have no friends and live by myself. I have no prayer of ever finding romance at this point, not for lack of trying. Every time I've made any progress the universe is always there to throw increasingly preposterous things in the works to sabotage it. The last time I had a social life in person was in my college days, but I lost them all from vicious bullying.
My efforts at making new friends or finding someone to date are only good for accruing the critical mass of suicide fuel I require for the inevitable day when I decide to succumb to that ultimate decision of despair. Every time I start talking to someone new who shares my interests, be it a potential friend or girlfriend, they'll always ghost me within a few weeks.
My romantic history is littered with brutal failures and "if onlys." In my entire life I've never been able to progress far enough to official boyfriend-girlfriend status. There is always something that will materialize to scuttle it.