Beautiful in White Lyrics Meaning

My mom and I argued about the meaning of this song, everytime i listen to this, it reminds me of a funeral.
It feels like the lyrics is the final message for his wife before her burial.

He's telling the listeners about the night when she saw her wife in a white dress, it's like her soul visited him, He was shocked when he saw his beautiful wife in a white dress. It feels like it was their wedding day,like it's the final piece of his puzzle. They reminisced about their memories.

Then,He promised that he will walk their daughter on the aisle for her wedding and that he will keep their love forever until his last breathe.