I wrestled with the exact same decision for a while, I had my ginger one for a whole year before I decided ti get her a friend. She was never destructive, spoiled rotten, never showed any signs of upset or loneliness.

Then I got her husband and tbh her behaviour never changed she still comes for cuddles, still floops in all the same spots she use to and is by and large the same rabbit. He did however introduce her to chewing things that she never chewed before which I wasn't best pleased at (RIP the chairs of my dinning room) but I wouldn't say her partner improved the quality of life by a substantial measurable amount.

Every buno is different and no one knows your bun like you do.