What you are witnessing is guys with thicker women but I bet when most of those guys met that woman that they werent thick. I see it happen on both sides. Most humans whether it is female or male usually tend to get lazy in a relationship and that means getting thick. The guy in his head probably remembers what she used to look like so it doesnt bother him. It is super shallow to just judge a woman on her looks alone. She might be wonderful at things such as cooking great, great provider, loving person, great with kids, cool to be around, etc. Looks is just one piece of the puzzle. There are other factors that you should look at that come into play.