Keep in the background

Hello,

keep in the background = not active, be quite, low key?

Thanks!

******

(by Salter)

The doctor has a bluff heartiness that is not at all excitatory, and his wife is soft spoken and polite. Both of them:
—worry over humiliating experiences,
—like to keep in the background on social occasions,
—are happy and sad by nuns without knowing why,
—consider themselves shy,
—are hurt badly by criticism, and
—are "very self-conscious" before superiors, and "in general" adds the husband