Related to this, we create non-unique table names for such one-to-one associations when using another association storage mode than IN_ENTITY. If e.g. one table per association is configured, we'd store the associations from Wife to Husband in a collection named associations_Husband which may conflict with other associations of the same name.

I think one-to-one associations should always be stored within the entity document, no matter what association storage mode is configured.