Kimi o koso sue no matsu to wa omoitsure hitoshinami ni wa tare ka koyubeki - Izumi Shikibu Nikki(English Translation & Meaning)

君をこそ末の松とは思ひつれ
ひとしなみには誰かこゆへき

Roma-ji: Kimi o koso sue no matsu to wa omoitsure hitoshinami ni wa tare ka koyubeki
English Translation: It is you, I thought,
who were the Pine Mountain of Sue,
the fickle one;
who else could ever cross it so,
like waves washing just the same?
Meaning: I thought it was you who were the Pine Mountain of Sue, the one whose heart might waver. Who else could cross my heart as waves do, just as you have?
Commentary: 15 The Carriage at the Gate and the Pines of Sue

The night after their moonlit exchange, the prince came to Izumi Shikibu, but she did not know it. Several households lived in different parts of the house, and when his attendant saw the carriage of someone who had come to visit another resident and said, "There seems to be a visitor; there is a carriage," the prince said, "Very well, let us go back," and left. He was displeased to think the rumors were true, yet he had no wish to end things altogether, and so he sent her a letter.
The woman is Izumi Shikibu, daughter of Ōe no Masamune and, as the wife of Tachibana no Michisada, Governor of Izumi, mother of Koshikibu no Naishi. The Prince of the Dazaifu is Prince Atsumichi, fourth son of Emperor Reizei, so called because he served as Governor-General of the Dazaifu.
The prince's letter, asking whether she had even known he came the night before, arrived with "Matsuyama ni nami takashi to wa miteshikado kyō no nagame wa tada naranu kana." It was raining, and thinking it strange, and wondering whether someone had told him a groundless tale, Izumi Shikibu sent back this poem.
Vaguely displeased about that night, the prince sent no word for some time. Only after a long while did he send "Tsurashi tomo mata koishi tomo samazama ni omou koto koso taezezarikeri."

The first three lines mean "it is you I thought to be the Pine Mountain of Sue," that is, the one who might prove fickle; taking up his "Pine Mountain," she retorts that it is rather he who should be suspected, sealed by an emphatic construction ending in a perfective auxiliary.
The lower verses ask "who would cross it just as you do?" where "hitoshinami," equally, contains "nami," waves, answering the waves of his poem, with a rhetorical construction. No man but he could cross into her heart; turning the very vow of the source poem to her own ends, she protests her innocence.
Author: Izumi Shikibu
Source: Izumi Shikibu Nikki
Prev Poem: Matsuyama ni nami takashi to wa miteshikado kyō no nagame wa tada naranu kana
Next Poem: Tsurashi tomo mata koishi tomo samazama ni omou koto koso taezezarikeri