What does it mean when your fiance calls a girl "sweetie" in a text?

So my fiance is texting a girl he used to be friends with through his roomie and recently got back in contact with. She lives in Pennsylvania and we live in Florida so I'm not too worried but I'm just wondering whats up. I went through his texts even though I know I shouldn't and their convo is pretty boring taking about his new job and her kids. However, he didn't mention anything about me or us getting married less than 2 months from now He said "nice pics" and sent one of himself to her, and then he called her "sweety." I never knew for my fiance to use this term lightly. They are both Puerto Rican and texting sometimes in Spanish so maybe that term is used more lightly in the latin american culture? Just an idea. Any insight will help. My fiance is not the cheating type, I've never had any problems before and I'm really happy with him. This girl just started texting him a couple of days ago and I can't sleep because of it. Thanks for help