marry above (oneself)
To marry someone who is of a higher social class or standing than oneself. A: "I hear that the local fishmonger's daughter is betrothed to a rich foreign lawyer!" B: "My word, she's certainly marrying above herself, isn't she?" For all the talk that social classes have been wiped away in recent years, you will still find people who believe one can't or shouldn't marry above oneself.
marry above oneself
Fig. to marry someone in a higher social class than oneself. They say she married above herself, but who cares? Scott thought it would not be possible to marry above himself.