Obviously she must be very sad, but this is her second marriage. Presumably her dad walked her down the aisle of her first one and the symbolism is all about handing her over from her ‘old’ family to the new.
Surely that doesn’t apply when you’ve been married before? My dad gave me away at my first wedding. I walked down the aisle on my own at my second because he couldn’t give me away, he’d already done that years before. It would have just been weird to have done it again IMO.