Based on what you know about them, why do you think Daisy is married to Tom?

In terms of family connections and old money, Tom is the perfect choice. They move in the same social circle, Tom can keep her in the manner to which she's accustomed, and they each understand their place... publicly and privately. All in all, I think the couple believed themselves to be in love or thought they had a relationship from which love would grow. None-the-less, the apiring would have been embraced by family and society.