He’s my partner, I’m his wife. He’s old fashioned like that, cute, but I’m not about to be betrothed to ANYONE in the near future.
Behold the next divorce based upon the pre-nuptial terms of endearment! 
In informal contexts, he’s usually referred to as “The Boy”. In more formal contexts, he’s “my spouse” or “my partner”.
I don’t like using “boyfriend”, even though it’s technically accurate, because it sounds awfully immature now that we’re in our 30s. It also implies that the relationship isn’t permanent or official, which is not the case here.
I’ll occasionally refer to him as “my husband”, mostly when dealing with house-related stuff like repairs, taxes and the like. It’s just easier that way, since it simplifies things for the person I’m talking to… a husband’s decisions/instructions are just as important as mine, whereas a boyfriend could be just some dude I’ve been seeing for a month and whose opinion carries no real weight.
Boyfriend, mainly, even though we are engaged. I call him my fiancé occasionally, but the word feels a bit old-fashioned to me. Dunno why.
On the other hand, I refer to his sister as my SiL.
Married here, but used to have an art professor that referred to her longtime live-in boyfriend as “My sweetheart Andy”. Adorable.
We’re both 52, both of us have teenaged children. But we find “boyfriend/girlfriend” works best. It took a bit of getting used to, but I quite like it now.
My sister the lesbian has referred to her “wife” for decades. She says that anyone who objects is immediately crossed off her “people I want to get to know” list.
17 years together, in our 40s.
Online - he’s my SO.
When I don’t want to bother to explain, he’s my husband. (ie, calling back a repairperson “My husband called you on Tuesday”
Otherwise, usually partner.
But I’m kind of liking Atomicflea’s “My sweetheart”
Spousal Equivalent.