I'm looking for a sourced reason for what purpose married women (as opposed to women who were never married) need to cover their hair. I have found that it is assumed that it is to make her less attractive, but have not found a source for that. Also, that would not explain why a divorced or widowed women needs to cover her hair. I also heard once, that it is to make her look more refined, but also no source.
The other questions on this subject only address the halachic requirements but not the reason for this obligation. I am not asking IF they have to cover but why. I'm clearly not asking about a divorced or widowed per se but married women in general.