Perhaps the old man had not known the depth of their feeling for him.

There is no possible way you could know the depth of feeling.

It took me a long time to understand the depth of their feeling about that.

The depth of his feelings for both her and the child.

He hadn't realized the depth of her feeling toward P-1.

Only he knew the depth of his feelings, be they fear or something else.

You may think that no one else can understand the depth of your feelings.

The depth of his own feeling came to him as a shock.

She did not pretend to understand such depth of feeling.

The depth of his feelings for her shows itself when she runs away.