As you use the term "partner" instead of spouse this alludes to the fact that you are defacto/significant others and not legally bound by a certificate. Therefore what is the requirement to take this person if not legally bound by paper?
I did not really want to go to the CX interview as a wife, but I went and had a great time. I really enjoyed the days alone to travel around HK by myself. It was good for me. I actually like HK and did from the first day there. I went out on my own. I went to places I most likely should not have been to and seen, but it gave me a better sense of the place. I learned about the housing aspect of things as I took the ferry over to Discovery Bay and looked at 5 flats there. Then I went and looked at 4 or 5 flats in Kowloon. What a shock I had about the size of a place for the amount of money they wanted. Talk about sticker shock!
If your "partner" has been less than charming and graceful in other socially important situations then definitely brief this person on the behaviour of "smile keep your mouth shut and speak only when spoken to and say very little then; just smile nod and say uh huh, oh yes and that's nice!" That is if this person has demonstrated total lack of breeding. But if your partner is charming witty and has a good head for polite cocktail conversation then by all means let that person be your front at the party. They (CX team) will only meet your partner at the party they will not ask your partner to describe the differences between a jet and turbo prop plane. They are just watching you and yours. This tradition is still held in many major corporations around the world. Unless they have some psychologist there observing from a corner saying "this one is serious trouble" I doubt you have anything to worry about, but then again, they may have a person doing the I Ching with the glasses you and your partner held to see what the all knowing says about you. Kind of like the dice cup in a game of backgammon you just don't know what the roll will say.
Having been the spouse "partner" that went to the interview I say take them. My husband used me as a sounding board and had someone to talk to after each phase, which can be better for you. It can help you to not worry so much about how you did and keep you from feeling so alone in a very different kind of place.
My husband was horrible in social settings. If ever there was the true essence of faux pas it was he. After the first event we ever went to it was a serious discussion about behaviour and what to and not to say at such events before we went. Perhaps your partner has more experience with being in such social scenes and can truly help you more than hinder you. ONLY YOU KNOW!
Just don't think it really has that much to do with you unless your partner really stands out in some adverse way. If you have doubts and you are not legally married then don't take the person and go alone, but be careful afterwards if you plan to say you want to bring this person after you are hired. The reason for not taking them would be as strong as there is no way we will be together if I am hired and then you arrive there with your bags and partner in tow..not too cool. Another thing is that this is standard procedures for all interviewees and before you even arrive on the scene you are wanting to be the exception. Does this project an image of desire to fit in with their corporate culture? Does this demonstrate the level of your cooporation to bend over for CX? Just some things to ask yourself.
Another thing about the spouse/partner going is that the visas will have to cover the two people or two plus offspring.