May offend Italian to English Art/Literary Idioms / Maxims / Sayings glossary/definitions

I know the word basically translates as "retreating" or "withdrawing" (as in from a room), however, it seems difficult to convey the sense of something sneaky taking place. Any suggestions would be much appreciated, slang terms and whatnot (AE or otherwise) given the register (quite informal) of the story. Two characters, an older man and a younger girl are about to sneak out for a moment of intimacy, etc. "Renzo e Vanessa scelsero di appartarsi in una stanza privata per sfuggire alla noia e ai rumori della festa."
Also, at a later point, the narrator uses the colloquialism in a bet he is making with a friend.
"Ti do 100 bigliettoni se stasera riesci ad appartarti con quella bionda...'' Gli dissi indicando la ragazza seduta al bancone."

Thanks all