Honestly I would like marriage depicted a bit more how it was back in the day. Where the vows were between a noble and the various alliances and land they would get, and give to, the other noble in exchange, with their children basically as collateral deposit for the transaction.
So much about this true love and fairy tale depictions of the nobility((Couslands)) in a land where calling out their defacto militaryl leader as a Kinslayer, Slave Trader, and Even having the queen come down to denounce them, only gets a slight "meh" compared to the "He went after nobles and their lands/titles" denouncement (Landsmeet).
There's a lot of whitewashing of nobility and power playing in dragon age. And since theirs is the only marriage that actually affects things ((Nobody would care about a ferelden refugee and a runaway elf hooking up in a same sex marriage if they weren't so socially high ranking)), its somewhat of a disappointment to see, at least from a plot standpoint.
EDIT: Added below,
Homosexuality itself doens't appear to be a big deal in thedas, unless your a noble. And that seems only because the nobility believes in heredical succession, that onlys those of a bloodline can hold a position of that specific bloodline. So if you're not into the kind of sex that makes babies, you're kinda the problem in the big "how to keep the family line going a few more generations" delima. Course, folks have been getting around this issue for years, mostly from getting into child making relationships and political alliance marriages, and having lovers on the side. This seemed to please most everyone, if not everyone, involved, until the church comes in and excommunicates everyone. Course, thats assuming the andrastian church frowns on that sort of thing, which is questionable at best.
Frankly I find the political aspects of marriage much more interesting then the sexuality aspects. Because when you break it down, all marriage is the same once you come down in the scale of power a couple have, and becomes the same boring machine of resentment and self-loathing its been for forever.