Ise Monogatari includes episodes of forbidden love with FUJIWARA no Takaiko, also as known as Nijo no kisaki, and also the younger sister of Imperial Prince Koretaka, Imperial Princess Yasuiko, who was a Saigu (a female relative of the Emperor sent to serve at Ise-Jingu Shrine).
ちなみに伊勢物語では、二条后こと藤原高子や惟喬親王の妹である斎宮恬子内親王などとの禁忌の恋が語られている。