Re-reading the Canto as a whole, particularly in light of 4.21 which likens Sundari's face to a lotus in a pond set off by duckweed, I have interpreted that what Sundari was painting on her cheeks was not so much a representation of a big moustache as specks of the duckweed-like stubble of Nanda's beard.
But even when the sage was there speaking the dharma,
And even though other family members
heeded the dharma,
Nanda passed the time in the company of his wife
Staying in the palace penthouse,
solely occupied with love.
For joined with his wife
like a cakra-vaka drake with a cakra-vaka duck,
And fitted for love,
He turned his thoughts
neither to Vaishravana nor to Shakra:
How much less, in that state, did he think about dharma?
For her grace and beauty
she was called Lovely Sundari
For her headstrong pride, Sulky Manini,
And for her sparkle and spirit, Beautiful Bhamini.
So that she was called by three names.
She of smiles as white as swans, eyes like black bees,
And swelling breasts like lotus buds jutting upwards,
Shimmered all the more, a lotus-pool in female form,
With the rising of a kindred luminary,
the sun-like Nanda.
For, with inordinately good looks,
And moves to match those heart-stealing looks,
There was in the human world at that time
Sundari alone among women, and Nanda among men.
She like a goddess wandering
in Indra's Gardens of Gladness,
And Nanda the bringer of joy to his kin,
Seemed, having gone beyond mortals,
and yet not become gods,
To be a Creator's creation in progress.
If Nanda had not won Sundari,
Of if she of the arched eyebrows had not gone to him,
Then the pair would surely have seemed impaired,
Like the night and the moon deprived of each other.
As though the target
of the God of Love and his mistress Pleasure,
As though the resting-place
of male Ecstasy and female Joy,
As though a bowl
containing male Excitement and female Contentment,
The couple took their pleasure together,
blind with exuberant desire.
Having eyes only for each other's eyes,
Their minds hanging on each other's words,
And the pigments that fragranced their bodies
being carried off by each other's embraces,
The couple carried each other away.
Like kimnara boy meeting kimnara girl
By a cascading mountain torrent, in love with love,
The two of them flirted and shone
As if vying to outdo one another in alluring radiance.
By building one another's passion,
The pair gave one another sexual satisfaction;
And by playfully teasing one another
during languid intervals,
They gladdened one another again.
Wishing to cherish his beloved
he bedecked her there in finery,
But not so as to make her beautiful --
For she was so graced already by her own loveliness
That she was rather the adorner of her adornments.
She put a mirror in his hand;
"Just hold this in front of me
While I do my face,"
She said to her lover, and he held it up.
Then looking at her husband's stubble
She began to paint her face just like it,
But, with a breath on the mirror,
Nanda took care of that.
At this wanton gesture of her husband,
And at his wickedness, she inwardly laughed;
But, pretending to be furious with him,
She cocked her eyebrows and frowned.
With a left hand left languid by love,
She threw at his shoulder the flower behind her ear,
And sprinkled over his face, as he kept his eyes half-shut,
The scented make-up
she had been using to powder herself.
Then, at his wife's lotus like feet
Girt in trembling ankle bracelets,
Toes sparkling with nail gloss,
Nanda bowed his head, in mock terror.
With head emerging from beneath the discarded flower
As he made as if to regain his lover's affections,
He looked like an ornamental naga tree
that, overburdened with blossoms,
Had toppled in the wind onto its golden pedestal.
Pressing him so close in her arms that her string of pearls
Was lifted from her bulging breasts, she raised him up;
"What are you like!" she giggled from above,
Holding an earring obliquely in her mouth.
Then, looking repeatedly at the face of her husband,
Whose hand had clung to the mirror,
She completed her face-painting
So that the surface of her cheeks
was wet with tamala juice.
Set off by the tamala marks, her face
With its cherry red lips,
and wide eyes extending to her hair,
Seemed like a lotus set off by duck-weed,
With crimson tips, and two big bees settled on it.
Attentively now Nanda held up the mirror
Which was bearing witness to a work of beauty.
Squinting to see the flecks she had painted,
He beheld the face of his impish lover.
Those painted flecks were nibbled away
at the edges by her earrings
So that her face was like a lotus
that had suffered the attentions of a karadava duck;
Nanda, by gazing upon that face,
Became all the more the cause of his wife's happiness.
While Nanda, in what almost amounted to a dishonour,
Was enjoying himself inside the palace in this manner,
The One Thus Come, come begging time,
Had entered his residence, for the purpose of begging.
He stood, facing downwards and not asking for anything,
In his brother's house
just as he would in any other's house;
And then, since due to the servants' oversight
He did not receive any alms, he went away again.
For one woman was grinding fragrant body oils;
Another was making clothes fragrant;
Another, likewise, was preparing a bath;
While other women strung together
The young women in that house were thus so busy
Doing work related to their master's romantic play
That none of them had seen the Buddha
-- Or so the Buddha inevitably concluded.
One woman there, however,
on glancing through a round side-window
On the upper storey of the palace,
Had seen the One Gone Well going away
Like the blazing sun emerging from a cloud.
Thinking in that moment of the importance
of the Worthy One to the master of the house,
And through her own devotion to the Worthy One,
She stood before Nanda, intending to speak,
And then, with his consent, spoke up:
"To show favour to us, I suppose,
The Bringer of Happiness, the Guru, entered our house;
Having received no alms, or welcoming words, or seat,
He is going away again, as if from an empty forest."
Hearing that the great seer had entered his house
And departed again without receiving a welcome,
He in his brightly-coloured gems and garments
and garlands, flinched
Like a tree in Indra's paradise shaken by a gust of wind.
Bringing to his forehead
hands joined in the shape of a lotus bud,
He then begged his beloved to be allowed to go:
"I would like to go and pay my respects to the Guru.
Please permit me, this once."
Shivering, she twined herself around him
Like a wind-stirred creeper around a teak tree;
She looked at him through unsteady tear-filled eyes,
Took a deep breath, and told him:
"Since you wish to go and see the Guru
I must not get in the way of your dharma-duty.
Go, noble husband, but come quickly back,
Before this paint on my face is dry.
If you dawdle,
I will punish you severely:
As you sleep I shall with my breasts
Repeatedly wake you and then not respond to you.
But if you hurry back to me
Before my face-paint is dry,
Then I will hold you close in my arms
With nothing embellishing them
save the moisture of fragrant oils."
Thus spoken to, and squeezed,
By a dissonant-sounding Sundari, he said:
"I will, my little vixen. Now let me go
Before the Guru has gone too far."
And so, with arms made fragrant
by her bulging sandal-scented breasts,
She let him go -- but not with her heart.
He took off clothes suitable for love
And took on an appearance
appropriate for the paying of respect.
She contemplated her lover leaving
With brooding, empty, unmoving eyes,
Like a doe standing with ears pricked up,
as she lets grass drop down
And, with a perplexed expression,
contemplates the stag wandering off.
With his mind gripped by his desire to see the Sage,
Nanda hurried his exit;
And then he went ponderously,
and with backward glances,
Like an elephant watching a playful she-elephant.
With her swelling breasts for clouds
and her full thighs for buttresses,
Her lean abdomen
was like a golden fissure in a rock formation:
Nanda could no more be satisfied by glancing at Sundari
Than by drinking water with one hand.
Reverence for the Buddha drew him on;
Love for his wife drew him back again:
Undecided, he neither stepped ahead nor stood still,
Like a king-goose waddling against the waves.
Once out of her sight
He descended quickly from the palace --
And then he heard the sound of ankle bracelets
And hung back, gripped again in his heart.
Held back by his love of love,
Drawn forward by his love for dharma,
He struggled on, being turned about
Like a boat on a river going against the stream.
Then he walked on with longer strides, thinking
"How can the Guru possibly not be gone?"
And "Might I after all embrace my love,
Who is so eminently loveable,
while her face-paint is still wet?"
And so on the road he saw, free of pride
And -- even in the city of his fathers --
haughtiness similarly absent,
The Possessor of Ten Powers,
stopping and being honoured on all sides,
So that it was as if Nanda were following Indra's flag.
The 4th canto in the epic poem Handsome Nanda,
titled "What He Begged His Wife For."