Grande went off after one follower tweeted, "The devil works hard but Scooter Braun works harder."
Like the Biebs and his new fiancee, Grande and Pete Davidson got engaged after what seemed like just minutes of dating. Following the news, one of Ariana's followers implied Scooter Braun -- who manages both artists -- may have had a hand in orchestrating the engagements for publicity.
"First Ariana get engaged to Pete Davidson and now Justin Bieber to Hailey Baldwin...the devil works hard but Scooter Braun works harder," the Twitter user wrote.
"You do realize we are human beings who love and have lives...right" she responded. "And that Scooter is a wonderful human being too who cares first n foremost ab our health and happiness? Love is lit. S--t happens. I hope to God it happens to you too. U deserve it."
She later deleted those messages.
Another fan tried to explain that it was all just "a stan twitter joke," adding, "we stan and love scooter."
"Okay okay," she responded. "Be nice to that man. He's wonderful. And very human. Always puts his artists' health and happiness first."
Bieber's proposal went down at a restaurant in a resort in the Bahamas on Saturday night. Everyone was salsa dancing when the pop star got down on one knee in front of the entire restaurant. Baldwin, 21, is the daughter of actor Stephen Baldwin and also host of "Drop the Mic" on TBS.