Because marriage is stupid. Women often get compensated too much in a divorce. Now, I’m not someone who thinks a housewife should just get zero alimony after a divorce. I understand that they forgo work experience to stay at home - experience that, if they had it, would result in a higher wage at whatever job they had to get after divorce. And that their contributions to the household also have substantial market value. But they get too much often times.
Also, once women get married, they know there is a huge price to pay for their husband to divorce them, and that they have him trapped. So they let themselves go, aren’t as interested in sex, don’t want to watch the fights anymore, or do any of the fun things they pretended to like during courtship.
That said, I am married. It’s tough keeping a woman around when she knows you won’t marry her. That is all they want in life. That and usually kids. That is their entire goal. And you can only string them along for so long.