I've been emailed lately by MauveLilly, who has informed me that Nabu did, indeed, propose to Layla! She says that since she has a friend speaks Italian who translated for her.
To confirm these beliefs, I immediatly rushed over to BanjoGate's video, and here is his/her translation of the event:
Stella: Am I wrong, or did someone want to tell us something special?
Layla: Well... Yes... Nabu asked me to marry him.
and then Sky asks Nabu...
Sky: Nabu, there is something that you wanted to say, right?
Yay! We all already knew that they would get married... but this is so cute! Later I'll get the whole proposal translation!