Cannot disable cascading removal of related entity

[ml1nk]

Describe the bug
There are two entities A and B. A is independent from B and B has only an OneToOne relation to A. As such B is the owner of the relation and the foreign Key is also the primary key of this entity. It does not seem possible to remove B without removing the related A, but it should be.

To Reproduce

@Entity()
export class A {
  @PrimaryKey()
  id!: integer
}

export class B {
  [PrimaryKeyType]: number
  @OneToOne({ primary: true })
  object!: CoreObjectEntity
}

The removal of B (orm.em.removeAndFlush) always triggers the removal of A.

Expected behavior
The removal of B (orm.em.removeAndFlush) leaves A alone.

Additional context
I tried different properties (orphanRemoval, cascade) of OneToOne and also switched to ManyToOne to get the expected behavior but none worked.

Versions

Dependency	Version
node	14.13.1
typescript	4.0.3
mikro-orm	4.0.7
pg	8.4.1