Is it permissible for the daughter of the sister to marry the son of the maternal uncle if the maternal aunt of the maternal uncle's son breastfed both of them two full feedings, and he is five years older than her, knowing that he was breastfed for a long period and she was breastfed two full feedings, and will she be sinful for continuing to love him?

The amount of breastfeeding that establishes prohibition is five discernible acts of suckling. Therefore, there is no prohibitory relationship between the two of you due to breastfeeding. However, it is preferable to refrain from marrying him as a precautionary measure. As for your love for him, you are not sinful for it, nor will you be held accountable for it, provided you are pious and ward off evil thoughts.