Answer:
He wants to add suspense and draw in focus. The long answer is elaborated below.
Step-by-step explanation:
The chorus is used to create a feeling of anticipation by foreshadowing what is to come in the future. The chorus mentions Romeo and Juliet's "death-marked love" several times, again hinting at their unfortunate demise at the conclusion of the play. He most likely also wanted the chorus to stand out and be more objective, rather than diverting focus onto one specific character.