While I don't know what caused the shift from "girlfriend" to "partner" in Hudson's speech, I do have some ideas.
Normally, calling someone "partner" often represents a deeper relationship commitment. However, based on what we saw Sunday alone, not to mention everything else prior, that doesn't seem to be a logical fit. Seeing the rehearsal photos with Sophie today makes it even more evident that Hudson was visibly happy with everyone else, but the partner. If anything, they seem more distant than at the Oscars. Now, who knows but Hudson and said "partner", but I'm not buying it.
The option I am moving towards is based on a combination of the nature of the event itself and my belief that this public-facing relationship will eventually terminate down the road.
Given that this was a formal event and speech, "partner" sounds more professional and serves as a shield that respects the bond of friendship while keeping the details ambiguous.
To the general public, it sounds committed and will not raise any red flags or invite prying questions about The Situation, while allowing him to step away from the term "girlfriend," a word he has objectively struggled to communicate publicly without stumbling over it - an odd tick to have for a supposedly long-term relationship.
Instead, everyone heard a respectful, modern term for a significant other. It locks down the narrative for the evening and perhaps for future use, respects her presence, and keeps her included in the milestone moment without continuing to use the girlfriend label that they know is Hudson struggles using. Partner is technically a more neutral term, while knowing the general public will likely interpret it as more, which seems to fit their current goal of social camouflage. It offers plausible deniability that the change was made as the relationship was evolving toward a more accurate, mature term that honors the friendship.
In PR, managing public transitions is all about controlling the narrative, reducing speculation, and buying time. "Partner" acts as an ambiguous linguistic shield. It satisfies the audience’s expectation that Hudson acknowledge her, but it conceals the underlying situation. Girlfriend carries romantic weight. Downgrading the romance of the term to "partner" flattens the emotion, especially given that the final, most significant thank-you was reserved for Connor at the end.
Just my two cents...and again, who knows!