As someone who likes to RP, I generally see marriage systems in MMOs as a very half-assed pandering to the typically mocked RP subset of the community. As well, anyone who truly wishes to RP a marriage, be it with a man, woman, midget, sheep, or whatever are absolutely free to with no coded backing whatsoever. That in mind, I feel the topical ********* can be outright avoided by not implementing marriage mechanics and simply letting people do their thing. The moment any kind of perks are added to the system like unique gear or other game features, you're basically asking for that swarm of players who feel their "thing" isn't being represented fairly.
At best, I'd say give a means to sign/engrave gear with a name and in the future have a paid name change service (RL or gil) so someone could adopt a new last name if they really, really, really want to.
Violence good. **** bad. Yay America.