"The Sims" is a fun simulation that gets some parts of life right. We all get cranky if we don't have enough fun, food, and rest. But when it comes to marriage, the game is very different.
Steps to Getting Married
Friendship is a requirement for Sims to get married. They have to have a relationship score of 70. Then it is safe to turn on the heat, by lots of kissing and hugging. The proposal action becomes available once the relationship score is met. In order for a proposal to be accepted, the potential spouse needs to be in a good mood. They can easily refuse the proposal just because they aren't hungry or need to empty their bladder. Once you are sure they are in a good mood, then propose. But even then, nothing is guaranteed.
The Wedding
When the proposal is accepted the Sims will immediately have a wedding. They change into wedding clothes and that's it!
After the Wedding
The visiting sim will move into the home adding their assets to the bank account. The last name of the Sim moving in is changed. Children of the new spouse will move in as well, except if there is another adult at the original home.
Divorce? New Spouse?
Once married, that's it! No divorce for Sims. They can, however, marry other Sims. Each Sim can have multiple spouses. A male Sim could have 7 other wives living with him, as long as he proposed to each in his own home.