The classics for couples: “honey”, “sweetheart”, “babe” and “darling”. They work between partners and, in some places, even casually with strangers.
In the family, you get “sweetie”, “pumpkin” and “buddy” (very common with kids and friends). Affectionate without being romantic.
Mind the context: calling a coworker “honey” can sound inappropriate. Nicknames require closeness and reading the room.
In practice
Couple“Good morning, sweetheart.”
Friends“Thanks, buddy!”
CautionAvoid intimate nicknames at work.