In doubting heart
that thinks I would forget—
that very doubt
makes all the more
my sorrow deeper than before.

Meaning

That doubting heart which thinks I would forget you—because of that very doubt, my sorrow is even deeper than before.

Commentary

Episode Twenty-One: "If I go forth and leave"

There were a man and a woman who loved one another and had no thought of turning their hearts elsewhere, yet over some trifling matter their married life became burdensome.
The woman left the house without telling him where she was going.

This poem conveys that the man truly cherished the woman who departed.
To have one’s feelings doubted by the person with whom one shared a heart is perhaps more painful than her very absence.

Source

Ise Monogatari

Other

Now that it is so, though one would sow the seeds of the grass of forgetting, would that even this were not left to another’s heart.
If only I might hear that you had planted the grass of forgetting— then I would know that you had truly thought of me.
Like clouds that rise and stand in mid-air, leaving no trace— so has my fleeting self come utterly to nothing.
Though it is bitter, I cannot yet forget you, for all your cruelty; and so, even in blame, still do I long for you.

In doubting heart that thinks I would forget— that very doubt makes all the more my sorrow deeper than before.

In doubting heart
that thinks I would forget—
that very doubt
makes all the more
my sorrow deeper than before.