And the eyes of those two Indian ponies Darken with kindness. (3-4)
Don't these lines just make you feel all warm and fuzzy? Love has a way of doing that. And kindness is one expression of love.
They ripple tensely, they can hardly contain their happiness That we have come. (9-10)
When people love each other, they are happy to spend time with each other; when separated, they can't wait to see each other again. The ponies' enthusiasm about the arrival of their human guests suggests a similar level of anticipation and affection.
They bow shyly as wet swans. They love each other. (11)
This line leaves no doubt that the ponies love each other; the image of bowing swans even suggests romantic love. By introducing the word "love" at this point, right in the middle of the poem, the poet brings the theme of love front and center.
And the light breeze moves me to caress her long ear That is delicate as the skin over a girl's wrist. (20-21)
Just as the breeze caresses the speaker, the speaker caresses the pony, making a further connection to the memory of caressing a girl's wrist. Sometimes, when two people are in love, they say, "This love is bigger than the both of us." That certainly seems to be the case in this situation. This speaker's interaction with the ponies seems to have triggered a mysterious current of loving energy that flows freely not only through the ponies and the people, but also through the universe at large.