Fair enough - but that definitely makes for a lonelier life! I can hang out with loads of different people whom I don't trust... but can still have a good time with them.

Unless you're just meaning that you don't talk about anything too personal with people you don't trust - which is totally fair! I've got my own set of "things I'll talk about with anyone" "things that seem personal that don't really matter to me anymore so I can share them" "things that aren't currently an issue but can be issues so I'll share this when I'm starting/trying to trust someone" and "things I'm probably not going to share at all and will only share if I DO trust someone".

haha. I think I'm a bit odd.