I have bad instincts. When I figured that out, I learned to watch out for the red flags, and now pretty much everything is a red flag to me. Talk about trust issues Anyway, there are some I feel are usually very accurate:

- The relationship you have moves from "barely know each other" to "you are the love of my life" too quickly. It may look sweet and romantic, and you may be so blown away by this other person -- but it's a major red flag.

- They make you feel uncomfortable, as if you were doing something wrong, without you being able to nail it down.

- They are secretive. They are unclear in what they say, and/or will not clarify it for you.

- They don't seem to recognise their mistakes, and if they do it was somehow -- mysteriously -- your own fault. There are no 'sorrys' without 'buts'.

All I can think of right now. Generally I'd say if it feels like a red flag, it mostly IS a red flag. Listen to your instincts, usually they are acting up for a reason.