You searched for: “absens haeres non erit
Absens haeres non erit.
Translation: "The one who is absent will not be an heir."

Sometimes it is also translated as, "Out of sight, out of mind." or "Absence does not make the heart grow fonder."

Karl wrote to his sweetheart that she shouldn't believe the old adage, Absens haeres non erit because I love you even more while you are away from me.