Recently I read a theory that everything/everyone in a dream is ourselves. The easy way to look at this might be - you dreamt she cheated on you and it is because you are scared of being abandoned. Another way to look at it is, you are the guy she was with, and you wonder how he feels, you are the girl, and you wonder why you make these choices.

I think this dream isn't because you are having BPD issues. It is just because there have been many changes in a short time and you are trying to understand it from every angle. It sounds like you want this to work out, and know that it is very soon to trust too deeply.

Some questions can only be answered with time. All the talking in the world won't prove as much as time. Relax and enjoy this new relationship. Try to live in the moment.

Life is a journey, not a destination.