Moving in

Last week I met my close friend, an ex-roommate, after a year. We chatted for only around 30min since she needed to go back to her hometown that day but it was nice. She updated her current situation, her father had a new business, she let her dad use her car, and..
next year she'll move in with her boyfriend!

Ok..she got me off guard there...

what do I supposed to say on such moment?
"Complimente!"?

She looked so excited about the plan so I guess that should have been a good response.
But, yet, I can't.

I mean...hello, in Indonesia you must get married first before you move in with your lover. It's a big big big sin (although maybe not seen as that severe anymore considering all recent extramarrital scandals). And anyway, even if you don't care about religion you better just do that unless you really really don't care about everything around you.

So, my first reaction that came in mind is, "What?are you going to get married this year?" :D
But, I realized then that might be improper...
also when I considered her all happy, brightened face.
So, I just made an "Oh" sound with a surprised-and-(tried-to-look)-excited-(too) look on my face.
But...really,..what should I have said?