If Murdered: Soul Suspect being on there is any indication, that list covers games where marriage is present rather than an optional thing you can partake in during the course of the game. You start M:SS already married, so it might not be quite what OP is looking for.

looks like you're probably right
i really like your username though

Sword of the Samurai, where it's of crucial importance to ensure the continuity of your dynasty.

Total War series, Sims of course

From what I have read, many of the Elminage games (but not Elminage Gothic) have a marriage option, which allows any two characters to marry and produce offspring (regardless of species and gender).

Also, from what I hear, recent Fire Emblem games have marriage (as does Fire Emblem 4 on the Super Famicom).

Some games have marriage as part of the plot, including Dragon Quest 5, Phantasy Star 3, and Lufia 2. In the first two of those cases, there are choices about who to marry.

A few games have marriages in their endings, like Final Fantasy 4 and Saga Frontier. (The Saga Frontier case is unusual in that the game never explicitely shows who the spouse is, and the most obvious possibility happens to be a same sex marriage--in a game that was originally released in 1997.)

Incidentally, I made a topic some time ago asking about games with same sex marriage:
http://www.gog.com/forum/general/games_with_same_sex_marriage

Edit: Regarding Saga Frontier, there are actually two marriages, the one in that ending I described, and one that is a different character's final boss fight. (That game is weird.)

Wait, I thought 'DOOM' was about marriage?

*rimshot*

Yes, I meant 2 and Aerie.

Hatred? :D

Since CK are dynasty games, it's a very central point of the game : No marriage means no heir, no heir means game over.

That said, if you play the alliance and inheritance game well, marriage can also be a very powerful political tool. At these games, a good wedding can be more devastating than a good war :)

Witcher 3...

The Royal Trap : Romance VN, so plenty of weddings to be had.

Embric of Wulfhammer's Castle : The protagonist is staying at the castle for her arranged marriage, and several of the path end up with a wedding.

King of Dragon Pass : You don't really play a character (you control a whole tribe), but the goal of the game is to marry your tribal king/queen to the leader of an enemy nation, to create a new kingdom.

+10 stress and -10 sleep irl ;-p

Yeah, games where the player can get married during the course of the game, not where the player is already married.

You can remove the "possibly" from long Live the Queen. Pretty much the game is about survival and marriage.

Defender of the Crown does this automatically, if I remember well, when you rescue a princess...