There are spouse dialogues that have a small (8%) chance to refer to you as one of the following "Term of Spousal Endearment" if you have 9 or more hearts with your spouse:
"Pookie"
"Love"
"Hot Stuff"
"Cuddlebug"
"Hunky" - If farmer is male
"Peach" - If farmer is female
"Cutie"
"Ducky"
"Handsome" - If farmer is male
"Darling" - If famer is female
If you don't hit the 8% chance you get:
"Honey"
"Dear"
"Sweetie"
"Hun"
"Sweetheart"
If you have less than 9 hearts you get the farmer's name.
Some of the relevant dialogues are: ({0} gets replaced with the term of endearment)
"NPC.cs.4440": "{0}, I hope our adoption request gets approved. I want a baby.$l",
"NPC.cs.4441": "{0}, I filed our adoption papers. Now all we can do is cross our fingers and wait.$l",
"NPC.cs.4444": "{0}, we're going to have a baby soon.$l",
"NPC.cs.4445": "{0}, I'm pregnant. Isn't it wonderful?$l",
"NPC.cs.4447": "{0}, we're going to have a baby soon.$l",
"NPC.cs.4448": "{0}, can't you tell? You're pregnant.$l",
"NPC.cs.4465": "Hi {0}! ",
"NPC.cs.4466": "Good Morning, {0}! ",