How many people should I book a hotel room for if I don't know how many will be there?

I'm really hoping the subreddit's name will save me here, because this is definitely one of my stupider moments lol.

So to elaborate, I'm booking a hotel room (on an event group rate, not sure if that matters) for an event that's almost a year away. This event is something I want to do with my partner. However, given how far out it is, neither of us are sure yet if they'll be able to make it. I want to get the hotel room regardless, which leads to my (less poorly-worded) question: should I book the room for one person, and add my partners name to the reservation if they can make it? Or should I book for two people, and talk to the hotel staff if they can't make it? Like... I guess what I'm asking is which of these would be less hassle for everyone involved, staff included?

Again, definitely one of my sillier questions, but it's eating at me and Reddit's never steered me wrong before... usually lol. Thank you!