As stated, both have a xayawaan or nolosha badda that a family is personally bonded to. From the time of birth, an Anima or Aquallia have a xayawaan/nolosha badda that is a partner for life. The bond between them is not something a non-Anima or non-Aquallia could understand. They are equals and thus great importance is placed on the two having a good and flourishing relationship.
While some have had their partner born at the same time as them, this isn’t always the case. It can take time before their partner is born and the longer it takes the more the void is felt. Another reason having offspring is so encouraged.
Should their partner die, it’s said that half their soul is lost. It’s not uncommon for grief to irreparably change the survivor in question nor is it uncommon for the survivor to soon perish after. The two were created in this world as one soul and can not survive it split in two.