Why some women let themselves go after marriage and child birth?

Zainab is an attractive young lady who maintains good hygiene and look after her appearance by wearing fashionable clothes and using makeup to appear more attractive. This habit of her makes her more attractive to most guys. Thereafter she was engaged and got married but shortly after she born children she let herself go. So what is the reasons behind this?

Some women let themselves go after marriage because of the following reasons

1. They look after their appearance solely for attracting partner: Men are very visual when it comes to sexual attraction; they obsessed strongly with women appearances, many of them don't care what woman look from inside or her attributes they only care how she look from outside. Girls understand this when they observe physically beautiful girls are the ones that most men stare at; the lack of attention some women get from men make them to use makeup to make men into thinking they are more attractive than they actually are. But now that they got husband and children they will feel there is no need to use their appearance to attract men anymore.
2. They suffer from depression: depression can make people to lost motivation on something they once do, a woman who suffer from depression will have no motivation to look after her appearance or do something she once enjoy.
3. Clubs and hanging out with friends is no longer their priority: Someone who always stay at home will have no motivation to wear fashionable clothes or use makeup compared to someone who is going to clubs and hanging out with friends always. Married women are unlikely to goto clubs or hang out with friends compared to single girls. Overall the great motivation for going to clubs is for attracting potential partner, but now that they secured husbands they will feel there is no need for going there.
4. Their identity and priority has changed: In psychology, we use "identity theory" to describe who someone is, identify the qualities, beliefs, personalities or looks that make a person. For instance we may say the identity of an 18 year old is teenager. Thus you will always find him listen to music, dating and using social networks. But you can't find a 50 year old doing so because his identity is not a teenager but father whose his job is taking care of his family.
   
   Some reasons why women let themselves go after marriage and child birth is because of identity and priority change. Prior to the marriage, their identity is "girl" and the girls main goal in life especially in developing countries is becoming housewives. Girls whose main goal in life is marriage can do anything possible to appear more attractive to men such as maintaining good hygiene, wear fashionable clothes, use revealing clothes in non conservative cultures and use makeup to impress and attract guys. But after they got married and born children their priority will change and so does their identity will be changed from "girl" to "mother". Mothers' jobs especially in developing countries are taking care of children, cooking and cleaning house not just looking after their appearance. Survey shows on average woman spend almost one hour a day on her appearance, this will be time consuming for housewives since they have other priorities.
   
   I found myself in similar situations even though I'm a man. I'm that type of person who spend a long time on my appearance but after I started learning coding my priority changed to the extent that I'm too lazy to even fold my clothes or ion them.
5. They no longer have competitors: women are value by men based on their youth and appearance, since dating is like competition any girl should either focus on her physical beauty or she will be left behind. But now that they secured husbands there is no other girls competing with them and this will make them to lost motivation for looking after their appearance.