Look up the word Affectation in the dictionary. You will find it is “behavior, speech, or writing that is artificial and designed to impress.” In other words, it doesn’t sound a like a real person. That’s fine if you want a character to appear as though they crave attention. If that isn’t what you were aiming for, you might want to rewrite the piece. That’s the reason we revise our writing. We want to fix all the problems that sneak into our writing. Affectation can creep in when you are trying too hard to write something.
Affectation is complicated, stilted writing. It is more formal, more technical or flashier than it needs to be. It cuts down on the readability of the piece. It’s an artificial voice or style. You should avoid it. Unless a character uses affectation to garner attention, it’s better to leave it out of your writing. It comes across as fake. That’s because it is. Develop your own voice. If it doesn’t sound realistic to your own ear, it won’t to anyone else’s ear either.
Take contractions for example. Having someone say cannot in place of can’t every time they speak is affectation. That’s because few people speak without using contractions. Not in English anyway. Not if they are native speakers. To speak with no contractions is, in English, very formal speech. Listen to people as they speak and you will find they often don’t even use full sentences. If you want natural sounding dialog in English, don’t be formal. Complete sentences are good in writing, but in dialog, you don’t need to do. Do what you can to ensure that the meaning is clear, even if you need another character to ask for clarification. That’s natural. Learn by paying attention the way people around you talk. That’s the best way to learn how to write dialog. Complete sentences work best for description. Although you can bend this rule to near breaking should you want to. At least you can do so in fiction. If you are writing from a particular point of view, it works as someone’s thoughts. Most of the time.
Having all your characters call each other darling is an affections. Especially if they aren’t in a romantic relationship, that’s an affectation. Not too many people do that. That’s not to say some people don’t call everyone darling, but that’s a person using an affectation to get attention. Unless your character is one of those people, it’s better to avoid it.
If you are uncertain of whether your work contains affectations, read it aloud. If the dialog and prose in your piece sound natural, you are doing it right. If it doesn’t, rewrite it. Your goal is to have your characters speak the way you would in the same situation. That’s natural. Your readers will thank you for it.