Kotowari ya omoi kurabu no yamazakura nioi masareru haru o mezuru mo - Kinyo Wakashu(English Translation & Meaning)

ことわりや思ひくらぶの山桜
にほひまされる春をめづるも

Roma-ji: Kotowari ya omoi kurabu no yamazakura nioi masareru haru o mezuru mo
English Translation: It stands to reason:
measured against Kurabu's
mountain cherries,
whose hues glow the brighter, you
should love that springtime more
Meaning: It is only natural: weighing one against the other, like the mountain cherries of Kurabu, you should cherish the spring whose colors glow the brighter.
Commentary: Book Eight Love Poems II 434

Weighing one against the other, the poet says, it is no wonder that the lover cherishes the spring whose colors glow brighter, like the mountain cherries of Kurabu. Likening a lover who has turned to someone more beautiful to a comparison of cherry blossoms, the poem reproaches with an irony tinged with resignation.

First line, 'kotowari ya', means it stands to reason, the poem breaking after the first line with the exclamatory ya. By inversion it returns from mezuru mo in the final line.
Second line, 'omoi kurabu no', is a pivot word in which kurabu means both to compare in one's mind and Kurabu, said to be the old name of Mount Kurama, left in kana.
Third line, 'yamazakura', is the mountain cherry blooming on Mount Kurabu, standing for the beloved.
Fourth line, 'nioi masareru', means whose color glows brighter, using ru, the attributive of the stative ri.
Final line, 'haru o mezuru mo', means that you should love the spring, standing for the new love of the lover whose heart has turned. It returns to kotowari ya in the first line.
Author: Unknown Poet
Source: Kinyo Wakashu
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