The way I usually do it is lower-case for indirect address ("He's my honey."), and upper-case for direct address ("Come here, Honey.").
"You take turns, advise and protect one another, even heal or be healed when the going gets too tough. I know! That's not a game--that's friendship!" ~Shelly Mezzanoble,
Confessions of a Part-Time Sorceress: A Girl's Guide to the Dungeons & Dragons Game Darcy\'s Place
