User blog comment:G0LD3NF1RE/E3 Elder Scrolls Online Roundup/@comment-67.251.70.113-20130618194118/@comment-6296105-20130619215307

Not precisely "marrying". Both players get a ring that boosts xp gain by 10% or something when they're playing together. And you can get multiple rings with multiple people. It's also quite expensive, apparently.