User blog comment:B214/Question and Answers/@comment-5882552-20130127034100/@comment-16281343-20130823103200

And also for those assumptions that they are already married, I think that that is not true, they are only engaged.

Because in a scene where Sirzechs's jokes about Ise calling him "Onii-chan", Grayfia reprimanded him that it is still not the time to do that but in the future, meaning they are already engaged but not yet married.