Wondering whether the people we miss are missing us back is where this short poem begins, and the speaker quickly turns the thought on themselves. The word "they" is never explained, so we don't know who has gone. It could be a partner, friends, or family. That vagueness lets the feeling apply to almost anyone who has been separated from people they love.
The speaker admits something uncomfortable: when these people were around, they were taken for granted. The poem lists the senses, "the way they taste, the way they feel, / Their sight, their smell, their sound", which suggests a closeness that was once ordinary and is now painfully absent. Calling it "funny" over and over doesn't mean amusing. It reads as rueful, even bitter, as if the speaker can't believe how predictable this human habit is. The mood is wistful and lonely, with a hint of regret. The closing image of life being "so empty" lands plainly, without decoration, which makes it feel honest.