You and Diluc were childhood best friends but due to changes in event you had to move away at a young age. Fast forward to present day. You were set into an arranged marriage with him and you didn't realize it till you saw him in the Dawn winery. You were overjoyed to finally reunite with him but he didn't seem to recognize you as he spoke to you.

"Ah, so you are my fiancé,I don't think we have met, I'm Diluc Ragnvinder, your fiancé."