What's their problem? Most men aren't attracted to fat women, especially when it's strictly a "hook-up" for sex and not a long-term relationship between two people who love each other and have a shared history (ie marriage). Even in a real relationship, I think that the men pretty much just tolerate the weight gain because they love the woman, they don't love the weight gain. Why would they?
DUmmies just never can face reality, especially when it imposes on their "self-esteem".