If you dont need to talk to them (they dont have an item you need or you dont need them to do something,) just dont talk to them
Viewing post in How do you get GLUTTON ending?
Basically only talk to the characters found around the game for nessecity and nothing else. (talk to Nala, get the key, never speak to her again except for when you need to later ask her to play the Piano. When she asks about if the worst happens, just say you would run. If you treat it like a speedrun you should trigger the Rebirth ending no problem.
If you mean confronting her in the piano room? It's not avoidable nor does it impact the ending. The only times there is optional chatter with her is after getting the key to the southwest section of the house and after surviving Mika the first time. Anything more than that is optional dialogue with her. Avoiding it and making sure to resist being prey whenever possible should trigger the Rebirth Ending.
I mean talking to her for anything other than story progression. Once you have the key you never need to speak to her again outside of interactions where the characters automatically speak, until you need to ask her to play the piano for you. You should tell her you would run when she asks what you would do in the worst case scenario. That alone should be more than enough.