Are You Okay, Sweetie?
Two things here.
1. When you ask “Are You Okay?” to someone in North American English, you are using these words because you already think something is wrong. In other words, you’re asking if someone is okay because you think they aren’t okay.
If you run into someone on the street, and you do not suspect that anything is wrong, then it’s best to stick with “How are you?”, “How’s it going?”, “What’s up?”.
In Britain, however, it’s normal to greet someone on the street with “Are you alright?”.
Hey, different countries have different cultures. Hopefully that excites you! 🙂
2. Sweetie is a term of endearment. It’s reserved for people who are very intimate (like Monica and Ross, who are brother and sister). In most cases, it would be unusual to call your friend “sweetie”. It’s mostly for use with family and people you love.