Circle crusher

Japanese slang uses the term “circle crusher” to describe someone, generally a female, who joins a school club (which are called “circles” in Japan) and sparks a breakdown in the friendship between existing members, often because of an active or desired romantic relationship.

"I heard Veronica broke up another group of friends again. Apparently she was secretly sleeping with all of them."
"What did you expect? She's well-known to be a circle crusher."