Help changing relationship thoughts

I am 44 years old, and I’ve never had a boyfriend. I’ve had plenty of unrequited crushes, I’ve had physical relationships because I’m human, I know I want an intimate relationship, I know that I’m straight… But it’s never happened. I know our thoughts cause our feelings and our results and I love your definition of lovability, but I have found it extremely challenging to not think there’s something wrong with me or to not think crappy-feeling thoughts like ‘no one has ever wanted to date me.’ I’m not sure where to start that’s believable. I have so much emotion, shame I think, about this that I’m really embarrassed even typing it here anonymously. Any first steps you could give me would be greatly appreciated.