Sorry, RG. Transitions are never easy.
We had a widowed family member who carried on as if nobody had ever known her depth of suffering. My Mom thought it was a bit much and so asked my Dad "name 5 things that would be better about your life if I died first?". My Dad, being a smart man who had been married over 50 years at that point replied "not a single thing". My Mom then pointed out that he'd no longer have to go to Garden Club meetings with her and he laughingly responded "that's so nice it should count for 2 of the 5"
I tend to believe a relationship with the right (for me) person is better than being single, but being single definitely beats a relationship with someone who isn't really right. Some advantages: I've lived in this house for over 25 years and there hasn't been a single fight here in all that time. No silent treatment, no sulking and no sarcastic or insulting comments. No doors slamming - just peace and quiet when I get home.
I can also afford to be selfish in my habits. If I want to eat out, sleep in, nap or watch dopey game shows from the 70's on tv, nobody is going to roll their eyes at me. Plus I don't have to listen to anyone else watching things all day that I think are annoying or stupid .
I also can prioritize my finances as I like. I don't have to spend money on trips that I don't really enjoy. Or buy cars or support other hobbies that I think are stupid.
I've known a lot of people who have mutually supportive and wonderful relationships, but I also know people who put up with a lot because they're afraid or don't want to live on their own. Ultimately, I think it's really about making the most and appreciating what you have, whatever that is.