I once played a campaign where me and another player agreed to play a married couple. I played a female paladin, and he played a male ranger.
The romance part wasn't too bad; we never got too..., um, detailed. It was even kinda fun at some points. My character got pregnant and had twins.
The real problem, however, was that the rest of the party was basically chaotic, including my character's husband. The game had a lot of politics, and the GM was pretty sympathetic to their view points. The characters would do all kinds of things behind her back, and it got really, really old trying to play dumb. The character just did not make any sense at all being in that situation. I wanted to retire her, but the marriage complicated things a bit. When I finally did, I think the husband's player was upset with me. He retired his character, too.
FM