CASE 1 My darling
to boyfriend : (firstname)くん~ or nickname in a deux
to girlfriend : almost say firstname or nickname in a deux
to husband : あなた~
to wife : おまえ~ or firstname
CASE 2 Friend's darling
to boyfriend : かれし
to girlfriend : かのじょ
to husband : だんなさん or だんな or ごしゅじん
to wife : おくさん or おくさま