They teach kids not to talk to strangers. I've never un-learned that lesson.
Three of my siblings have significant others. They are nice and I want to welcome them to the family. But I don't talk to them. I want to, but I don't know how. So I just smile at them to make up for it, and say positive things about them in their presence when I'm talking to my sibling.
Talking to strangers is a skill I need to develop.