Why do I always see hot guys with fat unattractive girls?

When I was a teenager I was really thin and beautiful, I was in love with this really handsome tall guy who had a girlfriend that was very plain and seriously overweight. I could never seem to get him to love me and I always wondered why because if you compared me to her she was like kirsty alley and i was like eva longoria. I never understood that. So then I put on a little weight right? This other guy I fall for leaves the thin girl he's with for me. I didn't start really getting guys until I was chunky. I was never rail thin, but I had a really good body, small waist and a butt. Now I'm overweight and have more confidence than ever with guys, and I see so many thin cute guys with fat girl. Is this just a coincidence?