Partly that depends on the couple, but how certain people relate to you tends to change somewhat. 'I' becomes 'we', which affects more things than you think. And there are certain expectations that come with it too; having a spouse is more exclusive than just a boyfriend or girlfriend, and it'll be expected that you'll devote a greater portion of your time and attention to them as a result.

Plus, of course, if you plan to make this official when you return to your own world, you'll have to wrangle with the various traditions and legal requirements there as well.