I'm 46 and single, not that I haven't been in long term relationships, I have. One was killed by a drunk driver and the others were simply cases of us growing apart and needing to move on in different directions in life.
When I was young, if you count my slut phase of one night stands, geeze 40, 50, maybe 100 fails but, the ones I wanted to be serious that didn't work out, maybe 20. I don't count something that worked for 24 months or more a fail, that's a break up for whatever reasons after it did work.
For now, I'm enjoying being single, working on my hobbies, investing time in projects I want to do for me and nobody else, making new friends, reconnecting with old ones etc... As for sex, I know where my toy box is and I can find my hands just fine thank you
Plus I have a few friends that are into phone and cyber, or collaboration on explicit fictional stories and that's a fun, safe release too.
If you think you have to be with someone to be happy, you need to look at yourself and figure out why you are not happy with you. Love yourself, if you can't love you how is anyone else supposed to love you? I know that's cliche but, it's true. If you don't like living with you, do you really think anyone else will? If you don't have fun with you, then what makes you think anyone else would find being with you fun.
Once you get that much together, the partner will fall into place when it's right for both of you and, it will work, maybe not forever, but, it doesn't have to be forever. Sure forever would be great, but so is each and every day that I'm happy with me and, having a partner whom I'm happy with and who is happy with me for even one day is a very enjoyable bonus, one to be treasured and, remembered fondly if (when) it ends.