Falling in love
Nhat Hanh describes falling in love as a kind of trick of nature. This is dramatic irony, because life's story-telling is so subtle that one only notices that one feels "in love" once it has already happened. "Falling in love," is only available for analysis in retrospect, and that is exactly what happens to this young monastic couple. They realize they are in some trouble emotionally speaking. Their most intimate emotional desire is now tempting them to break their oath. Nhat Hanh was snuck up on by feelings he didn't know would arise.
The monastic burden
To give up one's life for monastic purposes seems automatically noble, but for this couple, the sacrifice is infinitely more difficult and painful that they even anticipated. Instead of discussing their mutual feelings and then moving forward, they realize that a horrific fate has befallen them. Their love is the universe testing their love for one another; by rejecting each other, they can help the other person fulfill their divine oath to celibacy.
The dramatic irony of suffering
Nhat Hanh and his beloved are faithful to their vows. They willingly accept the suffering of life, which is the basic tenant of Buddhism, but ironically, their acceptance of suffering in one way amplifies the suffering they have to accept, exponentially. Luckily for them, this is not for nothing! There is a reward for their obedience to their vow. The cavernous hole left by his beloved's departure yields such an immediate and infinite source of sorrow that Nhat Hanh's meditation on this sorrow often leads him to states of acceptance, peace, and universal love for all of life.
The embrace
The story between these two monks reaches its fever pitch when they hold one another. This contrary tension between their forbidden desires and their oath lead to one unthinkably small concession. This one and only moment of physical contact between them is all they ever have in life. The irony of this is situational; by only indulging in physical contact one time, the hug is ironically powerful as a symbol for their sacrificed sexual and romantic desires for one another. This is their entire would-have-been marriage in one single embrace.