They haven't (yet). Well, all but in name. They're living together, they love eachother, and they both want to settle down, but Gideon hasn't put a ring on 'er yet. "Yet" being the operative word, because he does, and not too far long down the line.
Code:
Mod Note: Please use spoiler tags when talking about chapter-specific or future events.
@Aichan - if this story was an ecchi harem, one of them surely would have come to visit. Or maybe an ordinary schoolboy went to another world and ended up living with them.
Well, well, well. Ain't that nice that they already dunnit...guess we'll just have to wait for the chapter where she finds out she's expecting and they go for a shotgun marriage lol