"I'm getting off at the next stop, you murmur.
I am moved by the memory
of your sad and white flesh
and the humble companionship of your night,
the hand that you left
forgotten in my hand
as you came from the shower
just a moment ago,
while I refused to get up.

May you have a good day,
may good fortune find you
in your small, clean house,
may life treat you with dignity."

Luis García Montero, trans. JM

This is what I mean by sentimentality.

The advice to "avoid sentimentality" is probably useless. It is like saying "avoid writing bad poems." Sentimentality is dressing up one's feelings to make them sound more literary and dignified. Take what Luis is doing to his girlfriend here. He's basically dumping her, but needs to feel good about it so he dresses it up as a pious wish. Note the use of the word small, like Hall's "tiny." Sentimentalists love small things because they are more endearing, like baby animals. "May good fortune find you in your sprawling, messy mansion" would sound sarcastic. "Humble" works the same way. The attempt to make banal events fraught with meaning is another sign: "La mano que dejaste / olvidada en mi mano / al venir de la ducha...."