Would you consent to a 3-some for your partner if they were terminally ill?

Basically just what the question says. Came up in conversation at work and I was wondering what the general consensus would be.

So essentially frame it like this; your partner (be it girlfriend, boyfriend, husband, wife, whatever) finds out they are terminally ill… in our conversation it was with cancer… The partner has had a long time sexual fantasy of engaging in a 3-way with you and another person of a gender that “benefits” them. Would you consent too, or even potentially initiate said 3-way for your partner?

To help categorize it, please give some detail of your personal/specific situation. IE how long have you been together, have you been open to or even done such acts in the past, etc, etc.