Fuge would be fine.
Wrasses don't exactly pair like clowns do. They are like anthias in this regard; it's all about dominance. Even if it is a female and the new one is male, there will still be chasing/fighting until dominance/submission is established. Being a small tank, there might not be enough room for the little one to survive and get away if the chasing is bad enough, or likewise if the little one is unwilling to be submissive.