A long time ago, many marriages were arranged for financial or social gain.  The bride's family gave the groom's family a dowry to start the couple out in life. This money became his money. Later, marriages were for love, but the husband worked outside the home and the wife in the home still without access to money of her own. This stayed pretty much the same until the mid-1960s-1970s.

Where it begins:

Times have changed. Today, couples starting out have many more things to think about, such as who's going to pay the bills. Many people live on their own before getting married, so they're already financially independent when they combine household. By that time, it might be more difficult to let go of that control.   

Prenuptial Agreement  - Some might say these aren't very romantic, but if you have a significant assets or children, protect yourself, and them, with one.
Creating Marital Property  - When you get married you join your lives - and money, including property - together.
Joint Versus Separate Accounts for Married Couples - Even if you're married, you can still keep control by having separate accounts if that's right for you.
Joint Credit Cards - Maxxing them out or staying under the radar, know each of your limits.
Changing Names or Adding a Spouse to a Credit Card - When you decide that you partner can handle the truth. 
Add a Spouse’s Name to Titled Property and Accounts - There are more places than you think that you need to update names when you're married.

In a marriage or long-term relationship:Woman looking to man for money

Even if you're already married, or in a long-term relationship, it's never too late to protect yourself and family from money taking over your lives and coming between you.

Quick Tips for a Financially Healthy Marriage  - Just like a health check-up, you should both review your finances at least annually to make sure each of you know where you stand.  
Marriage and Filing Your Federal Tax Return - Don't we just love taxes? Here are some tips to help you file as a couple.
Filing for Bankruptcy as a Couple or Individual - It's the little things you do together - or not - like filing for bankruptcy.
Till Debt Do Us Part - For richer or poorer? Seems like a good idea, but how do you keep that promise if you have issues already?
Could Your Spouse Be Keeping Money Secrets - It's better to be up-front about your money problems before they lead to more problems.

Separating/Divorce:

It happens and it's nothing to be ashamed about. Whether or not it's money or something else that drives a wedge between you and your spouse, breaking up isn't easy. If you go into a divorce with property should you get it all back? What is your spouse really entitled to? When you've been together for a long time, how do you know where your property begins and your spouse's ends. 

Divorce: Property Division FAQ Set I  
Divorce: Property Division FAQ Set II