Final answer:
The quotation suggesting that love is rejected because of societal norms is the one focussing on the sacred law to intermarry among the Catalans.
Step-by-step explanation:
In the context of the theme that true love is more important than custom, the quotation that best supports the idea that love is being rejected due to societal norms is: 'Yes, you have been cruelly frank with me; but do you forget that it is among the Catalans a sacred law to intermarry?' This line clearly demonstrates how the pressure to adhere to tradition and customary laws can stand in the way of genuine love, implying that the speaker's desire to be with their loved one is being compromised by societal expectations regarding marriage within their community.