How did I mess this up?

I have been a member of the 7 cups community for awhile now and it has been helpful for me to open up about my loneliness as I really feel comfortable divulging my true feelings and experiences in this forum. It has been awhile since my last post in which I discussed the fact that I had finally met a girl but could not force myself to like her for superficial and physical reasons even though I was suffering through extreme loneliness and depression. There was simply no physical or other form of connection that I could develop with this person. It is perplexing to me that although I truly understand I am reaching the “end of my rope”, so to say, in the sense that i’ve never had a real friend or social support system in my life, I am 40 with no kids, and I know for certain my mental cognition is in serious decline due to lack of social interaction, I still could not force myself to try and love this person. Am I crazy? Should I have done whatever it took no matter the cost so that I can keep surviving? Well I decided to cut it off anyways and get a dog. This has really helped because I am now forced into performing certain daily actions like feeding the dog, taking it for a walk, etc. As time progresses however I still find myself very lonely. In response, I decided to try more dating sites and actually recently met a girl who lived 2 miles away from me. She owned a big house with a pool! She is smart, was willing to love me for me and cared for me, and introduced me to her friends. It was pretty much perfect and we just got back from a vacation. But guess what, she just dumped me. It was because of the same problems as with the first girl. Basically I could not force myself to love her physically the way she wanted me to because of her extreme case of obesity. I was so lonely that I would have done anything to break it so I decided to teach myself to love her this time. But In the first few months I known her I would sometimes joke and mention her taking a diet or commenting on her figure and little did I know my comments really hurt her and I had no idea. Sometimes when i tried to make love to her I simply could not get “ready” no matter how hard my mind wanted to and she noticed this too. It has been a few hours since she broke up with me and I have never felt more depression than I am feeling now. I just want to lay down in bed and not wake back up. How did I mess this up again? What could I have done to keep it going? Why did her outer figure have such an impact on me again. I simply could not control my body’s response. I know beggars can’t be choosers but I really don’t think I can be with a very obese person no matter how many good qualities they have. But at the same time, I obviously don’t look good enough to get the kind of girl I want either. So what should I do? Fake it? How long can that last? God I am so alone right now and right back at square one.