An artist might use a small scale for a portrait of a lover because it implies

An artist might use a small scale for a portrait of a lover because it implies INTIMACY.

Scale refers to the relationship of one object to another. One object may be bigger or smaller than the other object. 

In art, the terms used to refer to the scale of the artwork are miniature, small scale, full scale or life-size, large scale or larger than life, or monumental. 

Iwould recommend the attic

The artist above used rapid brushstrokes