无法在preRemove中更改和保存关联的实体

Question

I have 2 entities with association onetomany. 2-nd entity has 2 lifecycleCallbacks: prePersist and preRemove, that change 1-st entity. prePersist works fine, 1-st entity is changing in memory and is saving in DB. preRemove only changes entity in memory, without saving in DB.

Config:

ORM\Entity\TestUser:
    type: entity
    table: test_user
    fields:
        friendCount:
            type: integer
            column: friend_count
        friendReverseCount:
            type: integer
            column: friend_reverse_count
    ...
    oneToMany:
        friends:
            targetEntity: ORM\Entity\TestUserFriend
            cascade:
                - persist
                - remove
            fetch: LAZY
            mappedBy: user
            orphanRemoval: true
        friendsReverse:
            targetEntity: ORM\Entity\TestUserFriend
            cascade:
                - persist
                - remove
            fetch: LAZY
            mappedBy: friend
            orphanRemoval: true

ORM\Entity\TestUserFriend:
    type: entity
    table: test_user_friend
    ...
    manyToOne:
        user:
            targetEntity: ORM\Entity\TestUser
            cascade: {}
            fetch: EAGER
            inversedBy: friends
            joinColumns:
                user_id:
                    referencedColumnName: id
        friend:
            targetEntity: ORM\Entity\TestUser
            cascade: {}
            fetch: EAGER
            inversedBy: friendsReverse
            joinColumns:
                friend_id:
                    referencedColumnName: id
    lifecycleCallbacks:
        prePersist: [prePersist]
        preRemove: [preRemove]

ORM\Entity\TestUserFriend lifecycleCallbacks

public function prePersist($event)
{
    $this->getUser()->setFriendCount($this->getUser()->getFriendCount()+1);
    $this->getFriend()->setFriendReverseCount($this->getFriend()->getFriendReverseCount()+1);
}

public function preRemove($event)
{
    $this->getUser()->setFriendCount($this->getUser()->getFriendCount()-1);
    $this->getFriend()->setFriendReverseCount($this->getFriend()->getFriendReverseCount()-1);
}

tests

// works (friend_count increments in DB)
$userFriend = new \ORM\Entity\TestUserFriend();
$userFriend->setUser($user);
$userFriend->setFriend($friend);
$user->getFriends()->add($userFriend);
$em->persist($user);
$em->flush();

// don't work (friend_count without changes in DB)
$user->getFriends()->removeElement($user->getFriends()->current());
$em->persist($user);
$em->flush();