Why do women do this?

yes its simply a fact of the woman getting comfy in what she has, or stress in somthing she may b working to hard at somthing. its not just woman though, men r the same. most just dont acknowledge that fact cause more attention is focused on the woman. its no reason to cheat or resolt to porn. i would just confront her and say that shes been letting herself go abit, but in a nice way